At the state dinner for Portuguese President Antonio Ramalho Eanes last night, guests from Hollywood, New York and other points on the jet trails vied for White House honors in high fashion and expensive jewels.

And along with his formal dress, President Reagan wore his new hearing aid, leading TV talk show host Merv Griffin to say, "I think everybody's running out to get them whether they need them or not."

But there were serious moments, too. In his toast, Reagan said, "We in the United States understand the benefit of alliances between allies. We intend to help Portugal meet its military and economic needs. This is a simple matter of friendship."

Eanes, in his toast, said that "when Portugal lived under a dictatorial regime, it might have been considered an uncomfortable ally." But now, he said, "We are a responsible ally of the United States."

Reagan said he owed Portugal "a personal debt of gratitude" for another reason. "It was in 1542 that Portuguese explorer Joao Cabrillo discovered California--the state that is closest to my heart."

At the Rose Garden dinner, spectacularly illuminated with tiny, clear lights strung on shrubs and crab apple trees, guests dined on Maryland crab and lobster in aspic, supreme of capon in flamed brandy sauce, wild rice, timbale of green beans with garden carrots and spinach salad. The wines were Grand Cru Vineyards Dry Chenin Blanc 1981, Fetzer Cabernet Sauvignon 1980 and Chandon Blanc de Noirs Champagne.

"We prayed," said Ted Graber, Nancy Reagan's favorite interior decorator, of how the White House managed to get the weatherman to cooperate. Entertainment was also outdoors and as the night air grew chillier, some of the men removed their coats to wrap them around shivering shoulders. Assistant Secretary of State Richard Burt and White House social secretary Gahl Hodges, standing at the back of the crowd, solved the problem by holding hands.

"Frozen!" said actress Eva Gabor, who was lent a sweater and who came with Griffin but sat with White House Chief of Staff James A. Baker III. Griffin dined at Nancy Reagan's table, next to actress Lillian Gish. During the meal, Griffin kept craning his neck to get glimpses of Gabor, who appeared in deep conversation with Baker. Finally, she saw Griffin, and blew him a kiss.

Among the guests were Mary Kay Ash, chairman of Mary Kay Cosmetics; television commentator David Brinkley; actor Mike Connors; Henry Ford II; singer Sergio Franchi (who performed after dinner); Lockheed Corp. president Lawrence Kitchen; IBM president John R. Opel; actor Fess Parker; photographer Norman Parkinson; National Rifle Association president Howard Pollock; former New York Giants football player Andy Robustelli; Happy Rockefeller; Washington Times editor James Whelan and actor Richard Widmark.

Kathy Ford, in a black Ungaro set off by a glittering diamond necklace and large ruby earrings ("he's such a nice man, all the time," she said of husband Henry), was savoring her first White House dinner. "It's been a very comfortable evening," she said.

Lillian Gish, who received admirers as she sat on a bench lighted by Japanese lanterns, said she had been coming to dinner there since Calvin Coolidge first invited her. Bing Crosby's widow, Kathryn, on the other hand, said it was her first White House dinner. And the Duchess of Cadaval, who sat at President Reagan's table, made certain her souvenirs of the evening, a menu card and a program, went home with her.

Invited from the Hill were Sens. Dennis DeConcini (D-Ariz.), Jake Garn (R-Utah) and Frank Murkowski (R-Alaska) and Reps. Gillis W. Long (D-La.) and James Martin (R-N.C.). DeConcini, of Italian ancestry, joked: "Sometimes we're Greek, sometimes Portuguese, sometimes Hispanic--whatever the occasion warrants."

One member of Congress not invited was Rep. Tony Coelho (D-Calif.), chairman of the Democratic Congressional Campaign Committee, who described himself as the only member of Congress of Portuguese extraction. "This is Hispanic Week. I guess if I were Hispanic I'd be coming," an aide quoted him as saying.

For Secretary of State George P. Shultz it was a day of flowers. Tall floral arrangements in low crystal containers separated him from his Portuguese counterpart, Foreign Minister Jaime Gama. But earlier in the day at the State Department, when Shultz couldn't see Eanes because of flowers, Shultz took decisive action.

As Eanes, Defense Secretary Caspar Weinberger and 80 other guests looked on in amusement, white-gloved waiters at the fancy luncheon Shultz gave for Eanes whisked heavy vermeil stands holding arrangements of late-summer flowers off the tables and out of the room.

"These bouquets are beautiful, but the relationship between our two countries is a long and warm one, so we want to have these tables, which are small tables, lend themselves to conversations," said Shultz. "That's not possible through these bouquets on the table."

The luncheon was marked by a "Jefferson" theme emphasizing the setting, which was the State Department's elegant Thomas Jefferson Room. In addition to the vermeil flower stands, which State Department officials described as "typical" of the Jefferson era, there were placecards from an original design by Jefferson and menu cards with an etching of Jefferson.

Columbia Catering's chef Carlos Larangeira, of Portuguese descent, researched the menu of Colonial dishes that included bisque of Colonial crab with Indian corn sticks, veal birds with mushrooms, Monticello vegetable bouquetiere, Sally Lunn bread and apple torte with hot buttered rum sauce. Served with it were a 1981 Chardonnay from Montdomain Vineyard near Charlottesville and a California champagne.

Even President Eanes had a Jeffersonian touch to offer, noting in brief remarks translated into English that the third president was one of the negotiators on the first diplomatic agreement linking Portugal and the United States.

It was of another agreement, however, that Eanes, Shultz and President Reagan spoke yesterday, shortly after Eanes, with his wife, Maria, arrived at the White House to begin a state visit.

"Our security relationship is critical to the NATO alliance and both our nations," Reagan told Eanes.

The United States and Portugal currently are negotiating a new agreement that will maintain U.S. transit rights at the Azores islands' Portuguese air base.

"I am convinced that we can soon reach an agreement," Shultz told Eanes at the luncheon, where Chief of Naval Operations Adm. James D. Watkins, Air Force Chief of Staff Gen. Charles Gabriel and Sen. Claiborne Pell (D-R.I.) were among the guests.

Shultz handled his hosting duties alone because his wife, Helena, was out of town helping a daughter get ready for her wedding this weekend.

"I've been through this before. I know my role--write checks, stay out of the way and show up," said Shultz, father of five children. It's his youngest daughter, Barbara, who is marrying a Navy petty officer, but the State Department said it had no other information on the wedding plans.

At the White House arrival ceremony, the Eaneses' 11-year-old son, Manuel, became faint and was treated in the White House clinic, then released. According to Sheila Tate, the first lady's press secretary, the youngster apparently was overcome by the excitement and appeared to be "passing out" when a nurse was summoned. Both the Reagans and the Eaneses visited the clinic to check on Manuel. Guest list for last night's dinner:

Gen. Antonio Ramalho Eanes, president of the Republic of Portugal, and Maria Eanes

Jaime Gama, minister of foreign affairs

Joao Mota Amaral, president of the regional government of the Azores

Leonardo Mathias, ambassador of Portugal to the United States, and Mrs. Mathias

Jose Caldeira Guimaraes, chief of the civil household of the president

Adm. Henrique Silva Horta, chief of the military household of the president

Antonio Vaz Pereira, director general for political affairs, ministry of foreign affairs

Helder de Mendonca e Cunha, chief of protocol

Col. Jose Tavares Pimental, director of the Cabinet of the president

Luis Filipe de Castro Mendes, adviser to the president on foreign relations

Eduardo Ambar, director of the Cabinet of the minister of foreign affairs

Maj. Jose Barroca Monteiro, aide-de-camp of the president

Susan Mary Alsop

Mary Kay Ash, chairman, Mary Kay Cosmetics Inc., and her son, Richard R. Rogers

James A. Baker III, chief of staff and assistant to the president, and Susan Baker

Dr. Ralph Bohlmann, president, Missouri Synod Lutheran Church, and Patricia Bohlmann

Norman Braman, president, Braman Enterprises, and Irma Braman

David Brinkley, ABC-TV, and Susan Brinkley

Richard R. Burt, assistant secretary of state for European affairs

The duchess of Cadaval, New York City

Frank C. Carlucci, president, Sears World Trade Inc. and former ambassador to Portugal, and Mrs. Carlucci

Hays Clark, retired executive of Avon Products, and Ros Clark

James and Ida Clement, Kingsville, Tex.

Edwin I. Colodny, chairman, US AIR Inc., and Nancy Colodny

Mr. and Mrs. Michael Connors

Frank H. Conway, attorney, and Elizabeth Conway

Kathryn Crosby, Burlingame, Calif.

Trammell Crow, founder and senior partner, Trammell Crow Co., and Margaret Crow

James R. Currieo, national commander, Veterans of Foreign Wars, and Isabel Currieo

Michael K. Deaver, deputy chief of staff and assistant to the president, and Carolyn Deaver

Sen. Dennis DeConcini (D-Ariz.) and Susan DeConcini

Armand S. Deutsch, chairman, Starwood Corp.

Ahmet and Mica Ertegun, New York

Joseph E. Fernandes, president, Portuguese American Foundation, and Mrs. Fernandes

Martin S. Feldstein, chairman, Council of Economic Advisers, and Kathleen Feldstein

Alfonso G. Finocchiaro, president, Portugal/U.S. Chamber of Commerce, and Mrs. Finocchiaro

Henry Ford II, Ford Motor Co., and Kathleen Ford

William C. France, president and chief executive officer, Daytona International Speedway, and president, NASCAR, and Betty France

Mr. and Mrs. Sergio Franchi

Eva Gabor

Sen. Jake Garn (R-Utah) and Kathleen Garn

Lillian Gish

Ted Graber, interior designer

Merv Griffin

Enid A. Haupt, New York

Secretary of Health and Human Services Margaret M. Heckler and guest

Patrick Heininger and Maria Heininger

Reinaldo and Carolina Herrera, New York

Lupe Hinkle, Los Angeles

Malcolm Hoenlein, executive director, Jewish Community Relations Council of New York, and Frieda Hoenlein

H. Allen Holmes, U.S. ambassador to Portugal, and Mrs. Holmes

Rep. Henry J. Hyde (R-Ill.) and Jeanne Hyde

Lawrence Kitchen, president, Lockheed Corp., and Brenda Kitchen

Rep. Gillis W. Long (D-La.) and Cathy Long

Rep. James G. Martin (R-N.C.) and Dorothy Martin

Glen and Marilyn McDaniel, Los Angeles

Edwin Meese III, counselor to the president, and Ursula Meese

James Taxton Morris and Sara Morris, Albuquerque

Sen. Frank H. Murkowski (R-Alaska) and Nancy Murkowski

Ed and Patricia Nelson, Covina, Calif.

John R. Opel, president and chief executive officer, IBM Corp., and Carole Opel

Fess E. Parker Jr. and Marcy Parker

Jay A. Parker, editor, Lincoln Review, and Dolores Parker

Norman Parkinson, photographer, and Mrs. Parkinson

Kathryn Pate, president, Overland Steel

Samuel and Judith Peabody, New York

Sidney Petersen, chairman, Getty Oil Co., and Nancy Petersen

Joseph Peyronnin, CBS Washington producer, and Susan Zirinsky, CBS White House producer

Franklin B. Pollock and Elsie Pollock, Los Angeles

Howard Pollock, president, National Rifle Association

Andy Robustelli, former New York Giants football player, and Jean Robustelli

Happy Rockefeller, New York

Selwa Roosevelt, chief of protocol, and Archibald B. Roosevelt Jr.

Arthur Rouse, chairman, Good Sam Club, and Harriet Rouse

Dr. David Satcher, president, Meharry Medical College, and Nola Satcher

Farol Seretean

Secretary of State George P. Shultz

Gerald and Florence VanDerKemp, New York

James Whelan, editor, Washington Times, and Pamela Whelan

Gen. John A. Wickham Jr., U.S. Army chief of staff, and Ann Wickham

Richard and Jean Widmark

Ezra Zilkha, president, Zilkha and Sons Inc., and Cecile Zilkha