HIS DRESSING ROOM has that lived-in look.

Stamped-on cigarette butts obliterate the floor. Tape recorders, tapes, juice glasses, matchboxes, neckties, banjo strings, frets, drumheads, ashtrays, snapshots and a right-footed sneaker crazily litter the counter. Three banjo cases are stacked knee-high. And: banjos on stands, banjos on chairs, banjos propped against the wall. On the clothes rack, a sort of Orphan Annie wardrobe: seven identical pinstripe suits and 17 blue Oxford shirts.

Stephen Wade has been doing his one-man show, "Banjo Dancing," at Arena Stage's Old Vat for 36 weeks, a house record and nearly an all-time Washington record.

That's nothing. He ran 57 weeks in Chicago.

What does he do? Not much. He plays his various banjos, tells some tall stories, clogs a bit, hardly sings at all. At one point he runs around the house selling pens for 25 cents.

He'll tell you that none of his stuff is original, that the tunes come from the old Tennessee mountain players and the stories from folklore or Mark Twain or Leo Rosten.

It's Stephen Wade that is the original. A 28-year-old man obsessed by banjos.

He comes on from the back of the house, weaving his way among the customers at their little nightclub tables, saying hello here and hello there and absently plunking away on his five-stringer , finally leaping onto the spotlit stage.

As he talks, he plays the banjo. He handles it with the negligent precision, the perfect familiarity of a smoker with his cigarette. He picks one up, tunes it ("I saw Segovia one night in Chicago and he never tuned his guitar the whole evening. Some people just don't care . . . "), puts it back unplayed and goes for another. At the end, after his encores, raining sweat from his black Harpo curls, he says goodnight, but the people are still clapping, and his eyes slide guiltily over to that banjo propped on the chair, and he dives for it, slips it on with a heavenly smile -- the smoker inhaling the forbidden cigarette -- and he's off again.

After the two-hour show, he goes back to the dressing room. And keeps playing.

When he gets up after noon he reaches for a banjo. He runs a tape of Cordell Kemp or Eugene Bagby or Fleming Brown, his teacher, or Doc Hopkins, who taught Fleming Brown, or Uncle Dave Macon himself, and he plays along with it until he learns the new song. He will pick up a dozen songs in 10 days. He plays all afternoon, does his show, plays through the night, "maybe 12 hours, I never keep track." It's a tic.

Born in Chicago, Wade admits that he went to Wake Forest Academy and majored in English at Beloit College. He thought he was going to be a teacher. One night, 10 years ago, he heard Jerry Garcia of the Grateful Dead on banjo. That was it. That was the rest of his life.

"I do stroke style," Wade says. "It's called a lot of things: fraling, rapping, hacking, flying hands, drop-thumb, claw-hammer . . . It comes from the 1830s or earlier. Jefferson's slaves played the 'banjar,' as he put it. And the dancing and all, I think some of it goes back to the jesters in medieval England, which would explain why it wound up in Appalachia." YY OU WOULD THINK a Chicago prep school kid would Y have a tough time making friends with the isolated North Carolina-Kentucky-Tennessee hill people, who have no phones or bathrooms or money. Wade just drives up and asks if there's any banjo players around and talks a bit, and pretty soon someone mutters, "Well, play." So he plays, all bent over like Lon Chaney as the Hunchback of Notre Dame, and his skinny legs start jerking and his boots start slapping the ground and his brown eyes light up with a gentle, mad delight. And they accept him.

He has tapes that the Library of Congress would kill to get. He has Emmett Lundy of Galax, Va., telling how he made a fiddle out of a Civil War Army canteen with a Minie bullet hole in it, added a neck and horsehair strings, and played the thing. He has an old Georgia mountain man explaining how to play "Mulberry Gap" and saying, two weeks before he died, "If you ever play it for the people, just say you learned it from Chesley Chauncey." Which he does.

Once he cut his right thumb (he is lefthanded), and it wouldn't heal because on every other chord he had to put the cut right into the strings. "But you live with it," he said casually. "Now listen to this . . . ."