"When I'm calling you-oo-oo-oo-oo-oo-oo, will you answer true-oo-oo-oo-oo-oo-oo?" sang Nelson Eddy and Jeanette MacDonald in the 1936 film "Rose Marie."

Well, yesterday, fans of the long-dead screen duo answered their call and gathered in Washington's Grand Hotel to hear their songs, see their eight movies and stock up on Eddy and MacDonald memorabilia.

They said they are a vanishing breed, devotees of films that don't even get shown on the late late late show. But they came anyway, from North Carolina, Pennsylvania and across the Washington area. And some of them grumbled that their idols should have drawn 1,000 admirers to the fan club gathering, not the mere 100 people who showed.

"Before I got married, I saw 'Naughty Marietta' 52 times," said Mary Mosser, 69, of Fayetteville, Pa. "It's fun to see that I'm not the only crazy one."

And she certainly wasn't the only one wiping tears from her eyes and audibly sniffling when opera singers Micaele Sparachino and Sally Long performed "Will You Remember?" from the movie "Maytime."

The fans, most of them old enough to have seen the movies first-run, gushed over color photos, movie stills, recordings, even coasters, all of them bearing the romantic duo's now nearly forgotten faces.

"They were beautiful people. They had star quality that people lack these days," said Virginia Zemke, in her late sixties, who came to the Jeanette MacDonald/Nelson Eddy Friendship Club meeting accompanied by Julia Dill, 68, the same old school chum with whom she had seen the movies.

Once more popular that Fred Astaire and Ginger Rogers, MacDonald and Eddy made eight romantic musicals together from 1935 to 1942. They include "Maytime," the top grossing film in the world in 1937.

But after they married other people and stopped making movies together, the film couple's popularity waned. Both stars died in the mid-1960s.

"I didn't ever want to see them with anybody else, so I didn't go to his movies or her movies," said Dill, clutching her childhood scrapbook filled with pictures and programs about the screen duo. "Their voices blended. Nobody's voices blended like theirs. . . . I liked them equally, but being a woman, I was drawn to Nelson."

Not everyone at the gathering had fallen for the pair when the movies first came out. Darryl Winston, 36, who organized yesterday's meeting, watched the movies on television as a child. Being a MacDonald/Eddy fan "is kind of like a secret club. . . . It's wholesome and sentimental."

Philadelphia paralegal Maureen Kershaw, 35, said her mother "was going to name me Jeanette or Marietta, but my father and older sister" stopped her.

"I've got all the walls of my office covered with their pictures," said Kershaw, who spent $170 on movie videos yesterday. "This is like a little bit of heaven."

In the years after Eddy and MacDonald stopped making movies together, fierce rivalries sprang up among their fans, who organized separate clubs.

"The Nelson people thought Jeanette couldn't sing, and the Jeanette people thought he couldn't act. There was such hatred between them," said Sharon Rich, who helped found the fan club devoted to the couple and is now the club's president.

Now in its 16th year, the MacDonald/Eddy Friendship Club has 2,700 members and publishes a quarterly magazine, Mac/Eddy Today, which features a romantic portrait of the pair on every cover. The group's creed, which is included in all magazines and programs, proclaims: "You may love either one, but respect must be shown for both."

They may be few in number, but MacDonald/Eddy fans are persistent. MGM/USA Home Video officials said that in 1989 MacDonald/Eddy fans wrote the most letters demanding that the movies be released on tape. The Blockbuster video store in Cleveland Park had six of the eight movies on its shelves during a recent visit.

"They were great lovers," said Edward Brice, 64, of Arlington. He said that when he first saw them, "I was 8 years old and I wanted those two to get married. I couldn't understand why they didn't."

In fact, Eddy and MacDonald almost did -- several times -- and they carried on an affair for most of their adult lives, according to Rich, 39, who co-wrote a 1979 book on the screen couple and is working on a second one using a recently discovered cache of correspondence, including steamy love letters between the two.

At first, MacDonald turned down Eddy's offers of marriage because he wanted her to give up her film career, said Rich, who got interested in the pair as a teenager when she met MacDonald's sister.

Then, during the filming of "Rose Marie" and "Sweethearts," MacDonald twice became pregnant by Eddy and had two miscarriages, Rich said. At that time, MGM film studio head Louis B. Mayer forced the two to break up because he believed a shotgun wedding would destroy MacDonald's pristine image as "the Iron Butterfly."

But Rich contends that the on-and-off affair continued for decades, long after MacDonald married film star Gene Raymond and Eddy married Ann Franklin.

"When Jeanette died, Nelson went to the mortuary and put a ring on her finger that he had given her as an engagement ring when they were filming 'Rose Marie,' " Rich said.

Even some of the MacDonald/Eddy club members, however, find Rich's revelations controversial.

"If they can't say anything good, they shouldn't write anything," Bill McGuire, 70, told fellow fans as they sat together over lunch.

"I don't mind knowing the truth," retorted Stuart Smith, 72. "It doesn't denigrate her at all. . . . I loved Jeanette MacDonald and I wanted her to have a happy life."

"I don't want to know about the truth," countered McGuire, a voice teacher who lives in the District. "I don't want to hear about the miscarriages and the alcohol. We go to the movies for escape and entertainment."