To celebrate what would have been George Gershwin's 100th year, the New York City Gay Men's Chorus will devote its annual spring concert to songs from such hit shows as Porgy & Bess and Of Thee I Sing, with tunes ranging from "A Foggy Day In London Town" to "I Got Rhythm."

Titled "The Man I Love," the concert will take place at NYC's Avery Fisher Hall at Lincoln Center, March 29. Joining the Gay Men's Chorus, now in their 18th season, will be such stars as Debbie Gravitte (now in Broadway `68 downtown), Mimi Hines, K.T. Sullivan (Gentlemen Prefer Blondes), Jo Sullivan Loesser, Emily Loesser (Yiddle With A Fiddle), Audra McDonald (Ragtime, Carousel) and John Bayless.

McDonald is scheduled to sing "Summertime" and "Naughty Baby," while the Loessers will duet on "Somebody Loves Me." Mason offers "Swanee" and "Isn't It A Pity;" K.T. Sullivan sings "Someone To Watch Over Me."

For tickets ($10-$75) and information on "The Man I Love" call (212) 721 6500.

The 206-member choir will close its season June 22 with "Look to the Rainbow," a tribute to outgoing conductor Gary Miller. -- By David Lefkowitz