That Marvin Hamlisch is such a ham. He writes Oscar-winning music like "The Way We Were" and Tony-winning music like the score for "A Chorus Line," but he is jealous of the people who get to go out there and sing it and play it. And take bows. And get their pictures in the paper.

So he has made himself the celebrity composer. He has played Vegas. He goes on the Johnny Carson show and waxes funny. And he tours with what he calls "my symphony orchestra act - which I think is a wonderful act." One June 25, he will bring it to the Kennedy Center Concert Hall in a program to benefit the National Jewish Hospital and Research Center and the B'Nai B'Rith Women, because "They need a headliner and I need an audience," he says.

"Yes, definitely, a ham," says Hamlisch. "I love to perform, to be out in front of an audience. Royalties, true, they come in the mail, but you don't hear applause, you just get a check." He estimates that his share of profits on the Pulitzer Prize-winning "Chorus Line" will come to "a few" million dollars, but who cares about that? Hamlisch says he cares so little about money that he only spent 30 per cent of his income last year.

Hamlisch, 33, is sitting at the moment in a small and pretty drab apartment on the upper East Slide. This is not his apartment. His apartment is on Park Avenue. This is his mother's apartment. He is there because he is sick. And he looks sick - unshaven and wan. Even when he's well, the 6-foot-2 Hamlisch looks a bit like the big, dull blubbery kid in high school who nobody thought would amount to anything.

In this case, we were all wrong.

On the dinning room table at which he is sitting, the centerpiece of sorts is a bottle of Valium and two gooey Danish. Sounding like a polite little boy at a tea he says, "By the way, if you want one of these, please be my guest." (He means the Danish.)

Hamlisch used to be a Maalox man. "That was in my ulcer days." He even thanked the makers of Maalox when he accept one of his three Oscars a couple of years ago. "They sent me a case of Maalox after that, but I didn't know what to do with it. Perfume at least you can give away."

Composers throughout history have tended to be neurotic egomaniacs. We have no figures on this, but the gift to create music and the booby prize of certain emotional complexities, ahem, seem to go together. Hamlisch is afflicted with an addition to acclaim. It's the old approval syndrome with a vengeance. Not all the Oscars in Hollywood will shield him, he says, from an ungrateful critic.

"To me, the 'Chorus Line' score has never really been appreciated, criticwise," he complains with a wince. Critics loved the show but only liked the music. "That bothers me because I have in my mind that that score is just about letter-perfect.

"When people talk of the '70s, they'll talk of 'Chorus Line.' It'll be The Show of the '70s. I'm extremely proud of it, it's everything I wanted it to be, a huge commercial hit but very artistic. They all said it couldn't be done, and I'm proud that we were able to pull that off."

Less glorious perhaps was the Hamlisch triumph on "The Sting." Though he accepted an Oscar for scoring the film, the music had been written years earlier by Scott Joplin and much of it was orchestrated by Gunther Schuller. Obviously this is a sore point with Hamlisch.

"First of all, I still maintain that I brought Scott Joplin to mass appeal, number one, and number two, I think it's really interesting that Gunther Schuller might not have gotten credit but he's getting money that he doesn't seem to grumble about off the score. Number three, I was accused of not having mentioned Scott Joplin's name at the Academy Awards which is not true because I did; I have the video-tape and I can show you that I did."

Hamlisch just completed his first movie score in two years, for the upcoming James Bond picture "The Spy Who Loved Me." Scoring films is not Hamlisch's favorite job. "It bothers me to be writing, quote, background music, because if I'm not writing forefront music, what am I writing for? I see movie music as a means to an end. I try to get a hit song out of it, so I still have a chance to write the forefront stuff. You know what I mean?"

Yes.

Hamlisch is asked if he can remember the first song he ever wrote. "Yes I can. It was at the age of 7 and it was called 'My Billy Boy.' It's terrible. The opening line was, 'One day I was awalking to find my Billy Boy; he was gone, he was gone, he was gone.' One of your real big hits. I knew then that I would not go into lyrics."

He can also remember his one and only commercial jingle, sort of. "It was for - wait a second - it was for Sears, uh, oh yeah, I know, it was Kenmore. I remember distinctly how it went because I wrote two jingles, one that I loved that was real good and was immediately turned down. They told me they wanted something instantaneously hummable so I wrote the most banal thing I could think of and that's the one they accepted.

"And it went (he sing, slapping the table in rhythm): 'Duh-duh, de duh-duh-duh-, You always get more, with a Kenmore, 'Cause Kenmore has so much more to give - duh he duh-duh - You get more a Kenmore and get more savings, so get a Kenmore and get more, time to live, ba ba ba bah.'

"The other one I can't remember right now, but boy it was hip. It was so Laura Nyro hip. And they said no."

Hamlisch has the guts to sing in public, too, as part of his symphony act. "I just wish I had a better voice, because then I would become a singer." Applause, applause. "I sing, but hardly. It became kind of a thing where critics would say, 'Although he doesn't have a wonderful voice -' one of those 'although' sentences in there, so now I only sing once during the show."

He is now at the crossroads of deciding "how commercial" he wants to be, Hamlisch says. "I think one should do it. Again you leave yourself open to great criticism but I think it should be done.

"Composing is a tough life. People think you have a hit and the money comes rolling in, but that's not the problem. That creates the problem. Now I have to think, 'How can I beat "Chorus Line," what can I do now to satisfy my need to write something as good?' And that is a much a much bigger problem than worrying, 'Where am I gonna get the dollar-fifty for the hamburger tomorrow?' You cannot sit down and write it and say, 'If it doesn't come today, I'm gonna kill myself.' No, you can't do it.

"I just wish I weren't so tough on me in terms of what my expectations are of me. I wish I could just sit back and relax and let it happen."

Hamlisch had been out shopping earlier trying to find "just the right cuff links" for this Kennedy Center appearance. "Simple, plain onyx. Nice, you know. I looked at the sapphire ones and saw how much they were and I said, 'Forget it.' Not that I'm cheap and frugal, but I have priorities. I went tothe Tony Awards in a taxicab. And when I came out, I said to somebody, 'You wanna see my yellow limousine?'

"I'm not taking this Kennedy Center concert lightly at all. 'I've done a lot of preparation. And I think I've put together 90 pretty fabulous minutes."

Hamlisch will conduct 70 musicians in Gershwin, Joplin and, oh yes, Hamlisch. He will have the subline pleasure of performing his ownmusic in front of an audience. Of having one's Valium and taking it, too. He is absolutely unashamed about the pleasure he gets from this.

"That's what I do," he says. "So if that's what I do, that's what I do."