For years, some of the oldtimers recall, the annual midwinter dinner of the Metropolitan Washington Board of Trade was a boys' night out. It was a chance for the fellas to put on black ties and tuxedos, eat a big steak and sip a little sauce, hear a few good jokes and affirm that boys will be boys, in almost every imaginable way.

The board, the city's most powerful business organization, was a nearly all-white, very clubby and politically conservative set, which included some of the financial blue-bloods of the District and its Maryland and Virginia suburbs.

Now the board is changing, trying to adjust to the new fraternity developing from the fluid character of this metropolitan region, where at times power relationships appear to be shifting and the old elite must scramble to hold its place.

Still, there were some clear signs Saturday night that the change is not complete. For example, the night's entertainment included a trio of black tap dancers known as the Third Generation Steps, descendants of the famous Step Brothers, who smiled non-stop, waved their hands and slid, skipped, somersaulted and soft-shoed across the stage, to the wild and sometimes shrieking delight of the audience.

Then there was some of the humor - like master of ceremonies WIllard Scott's impersonation of Israeli Prime Minister Menachem Begib. Scott's Begin tersely concluded a summit meeting with Egyptian President Anwar Sadat by saying, "Sadat's dat."

The changing times were evident by the murmurs and grunts the Sadat joke brought, the shame some of the organization's highest-ranking members confessed privately about the trap dancing routine and the number of blacks, Jews and women in the audience of 1,000.

Indeed, for the second time in three years, the president of the group is Jewish (lawyer R. Robert Linowes; Joseph Danzansky was president in 1976). Of the 80 members of the board of directors, more than a dozen are blacks or women.

Many of those familiar with the board's history talk about the change. One symbol of the change, they say, was the retirement last year of aging Clarence Arata, executive vice president, and his replacement by his young former assistant, John R. Tydings. Equally important, they note, is the presidency of Linowes, whose law firm, Linowes & Blocher, included the zoning lawyers most intimately involved and well-connected during the building boom in Montgomery County several years ago.

Among the things Linowes brings to the board is a new effort to attract suburban businessmen. Symbolic of that effort at Saturday night's dinner was the presence of Acting Maryland Gov. Blair Lee III and Sen. Charles McC. Mathias (R-Md), who sat with Linowes and D.C. Mayor Walter E. Washington.

Linowes also has a keen understanding of the necessary relationships between business and government. To wit, more than a dozen D.C. City Council members and ranking officials in Mayor Washington's administration were given reserved seats at one of the seven tables purchased by Linowes' firm.

Another sign of what the Board of Trade is about these days was included in a 2 1/2-minute film shown at the dinner, which was produced for the board's use in encouraging businesses to move to the Washington metropolitan area! The color production had an original folk-rock theme song, scenic shots of monuments, children playing in the park, youngsters dancing in the discos and only two clearly identified black faces.

Last year, when a reporter spotted Council Member Douglas E. Moore at the Board of Trade dinner (sitting at the table of then Board President Foster Shannon) Moore said he had come only as "the spook who sat by the door."

This year Moore was at the dinner again, and again at one of the tables sponsored by the present board president. Moore says he is still sitting by the door and spying on the Board of Trade.

Shannon, at least, must like spies. At a party in Linowes' suite later that night, Shannon joked that he is going to call a press conference soon and endorse Moore for election as Council Chairman because, Shannon said with a smile, "Doug's my main man."

Ironically, Moore was one of the those City Council members who did not attend the dinner of the predominantly black D.C. Chamber of Commerce held the night before.

Last year, in the wake of reports questioning the ties between himself and millionaire parking lot magnate Dominic F. Antonelli Jr., City Administrator Julian R. Dugas was seen sitting at the same table with Antonelli. This year, however, Dugas sat at a Linowes table, and Antonelli sat at a table that did not include any city officials.

In some respects, the state of business advocacy is another of the remaining segregated institutions in the nation's capital. For half a century, most whites have belonged to the Board of Trade, while most blacks have joined the D.C. Chamber of Commerce.

About 600 people attended the chamber dinner Friday night at the Sheraton Park Hotel, where keynote speaker Richard L. Lesher, president of the U.S. Chamber of Commerce, attacked the federal government as "bloated, stupid and an unnecessary meddler in the affairs of business."

"Taxation, regulation, inflation - the biggest problems for small business. It is no coincidence that they are all caused by government."

The split now is between those who care more for socialist ideology than for the poor, and those who care more for the poor than for ideology."

That kind of do-it-yourself approach was a bit too much for some chamber members, who said it was too early for blacks to rally around the cash register and tell the government where to go.

"There are really two first grades," chamber President Larry C. Williams Sr. said afterwards. "For thos who really started in the first grade, like him, that's a good platform. But the black and minority businessman is in kindergarten and only thinks he's in first grade.

"They will reach parity only by the joint efforts of business and government. They cannot raise themselves by their bootstraps."