There's a new chorus in town. It will be heard in its debut concert today (and again on Friday) in St. Mark's Episcopal Church on Capitol Hill.

The group is the 110-voice Gay Men's Chorus of Washington, now 8 months old. It got started last June when the San Francisco Gay Men's Chorus sang a magnificent concert in the Kennedy Center for an audience of over 2,200. Before that night was over, plans were underway for adding Washington to the growing list of cities with gay men's choruses: Chicago, New York, Seattle and Portland, Los Angeles, Minneapolis and St. Paul.

"We represent a cross section of the greater Washington community," said Everett Waldo, one of the founders and chairman of the chorus. "We are teachers, doctors, lawyers, waiters, government workers and writers who have come together to make music and to share our enjoyment with the entire Washington community." Said Mike Ziskind, who works on community relations, fund-raising and publicity: "There is something special in singing with other gays and in sharing their love of music."

Most of the men in the chorus have sung in college glee clubs, and at a rehearsal last fall they eagerly called out the names of their schools: Harvard, Yale, University of Iowa, University of California at Riverside, Princeton, Vassar, University of Michigan, Indiana, Villanova, William and Mary, Wisconsin, Georgetown, Davidson, Ohio State, Syracuse, West Point, University of West Virginia, Maryland. Since there is a magnificent repertoire of music written specifically for men's voices, it is a fortunate coincidence that gay men's choruses are appearing on the scene at the same time that men's glee clubs are disappearing from many of these campuses.

There are no restrictions to membership in the chorus, but when asked, "Is everyone here gay?" the men's answer came in an affirmative roar. Although several men asked that their names not be used, not one of them moved when given the opportunity to leave before a photographer snapped the group.

"Five years ago half of the men would have stepped out," said Ziskind. "These people are comfortable with themselves. We have become like a family . . . We don't take ourselves too seriously."

Although some of the men have never sung before, about half have sung in church choirs, and perhaps a third have studied singing. A number also have sung in some of the major choral organizations of Washington: the Choral Arts Society, the Oratorio Society, the Cathedral Choral Society and the Army Chorus.

The new conductor is Nick Armstrong, a graduate of Virginia Commonwealth University, who has done graduate study in conducting. He started at a salary of $100 a month, which the chorus plans to increase as it is able. The conductor of the San Francisco chorus is paid $1,000 a month.

The Washington chorus pays its expenses--the cost of music plus $60 a night to the First Congregational Church for the rehearsal room, and other items that arise in building a new musical organization--out of monthly dues of $6 and voluntary contributions.

Already the chorus has become involved in community projects. They sang last fall in the District Building at the request of Mayor Marion Barry, and at a Christmas concert in the Metropolitan Community Church, at which time they organized a "Toys for Tots" drive to which each member contributed.

On the program tonight are 20 songs ranging from the traditional "Sometimes I Feel Like a Motherless Child" to three Shakespearean songs to "Standing on the Corner."