NEW YORK - Alvin Epstein has died 100 times onstage.

''But I've never played anybody who's died through the course of the whole play,'' said the 77-year-old actor, a longtime member of the American Repertory Theatre company.

Epstein has taken on that daunting task in the title role in ''Tuesdays With Morrie,'' a stage adaptation of sportswriter Mitch Albom's phenomenally successful 1997 memoir of life lessons he learned at the deathbed of his former Brandeis professor Morrie Schwartz. The play, which began preview performances yesterday at the Minetta Lane Theatre, officially opens Nov. 19.

''It's a fascinating and complex role because Morrie's personality is very unusual,'' Epstein said recently, sipping coffee outside a Times Square rehearsal studio. ''He's a man who finds out he's dying of an incurable disease, who decides to turn it into a teaching tool - and who wants to share it with as many people as he can.

''Morrie also died of what happens to be a devastating disease,'' Epstein said. The disease, amyotrophic lateral sclerosis (ALS), is better known as Lou Gehrig's disease, a neuromuscular disorder that weakens and eventually paralyzes the muscle system.

The debilitating illness progresses quickly. In the opening scene of ''Tuesdays With Morrie,'' the actor said, his character is dancing. ''Then, over 90 minutes, he goes from using a cane to using a walker to a La-Z-Boy, a wheelchair, and then to a bed.''

Conveying Morrie in life, and as a life force, is a singular challenge. ''Playing a man who really lived - who really existed - is a big responsibility,'' Epstein said. ''But then, every role is a big responsibility.'' What makes Morrie different is that he is a ''national figure.''

Indeed, he has become an American icon.

Three weeks before he died at his home in West Newton in 1995, Morrie - as he wanted everyone to call him - appeared on ''Nightline'' with Ted Koppel for the third and final time. ''I'm going to die,'' the white-haired wise man told television viewers. ''But I'm also going to live on.''

That optimistic promise turned out to be an understatement.

Albom's book, which he and his former teacher collaborated on to help pay Morrie's medical bills, has sold more than 5 million hardcover copies since it was published in 1997. (Albom splits the royalties with Morrie's widow, Charlotte, and their sons.)

Released in paperback for the first time last month, ''Tuesdays With Morrie'' shot up the New York Times paperback bestseller list almost immediately. It's currently No. 4 on the list.

The story was made into a 1999 Emmy-winning TV movie starring Hank Azaria and Jack Lemmon, and public appetite for Morrie's homey aphorisms about living wisely and dying well (''Aging is not just decay, you know. It's growth'') has burgeoned since. The insights imparted by the simple-living, plainspoken elderly professor to a sophisticated, successsful, but spiritually unsettled baby boomer have turned into touchstones in sermons, motivational speeches, the literature of death and dying, and the wider self-help movement.

''When you're playing a person who was alive, there is a responsibility to some sort of verisimilitude,'' said Epstein.

He has faced this responsibility before, when he performed the role of Lee Strasberg, the legendary proponent of Method acting and director of the Actors Theatre, in Robert Brustein's 1998 play ''Nobody Dies on Friday,'' about Strasberg, the Method, and Marilyn Monroe. In that case, ''I had the good fortune to have gone to the Actors Studio,'' said Epstein. ''I knew Lee and observed him and watched him. It was very helpful in playing a figure who is a legend.

''I never knew Morrie, and I have studiously avoided watching the television tapes'' of his appearances on ''Nightline.'' ''I don't want to hear them. I don't want to imitate in any way.''

In creating the character, Epstein continued, ''I am working from things in my own imagination and things that are told me by Mitch Albom. I can't hope to become Morrie for people who knew him. What I can hope is to suggest inner qualities that he had.''

Epstein's career, which spans nearly six decades, has been filled with the sort of episodes and experiences from which great theater memoirs are made. He is simply too busy working to write about his lives on the stage.

A versatile ART regular known for his interpretations of Brecht and Beckett and for his evocative cabaret performances of the music of Kurt Weill, Epstein is also a singer, dancer, and director.

He studied with Martha Graham and performed with Marcel Marceau. He played the role of Lucky in the American premiere of ''Waiting for Godot'' and the Fool in a ''King Lear'' directed by Orson Welles. Epstein directed the ART's inaugural performance of ''A Midsummer Night's Dream'' at the Loeb Drama Center and performed with Sting in ''Threepenny Opera.'' He also taught at Yale and Harvard and did a brief stint as artistic director of the Guthrie Theatre in Minneapolis.

In the summer of 2001, Epstein took part in a workshop production of ''Tuesdays With Morrie'' at the Eugene O'Neill Theater Center in Connecticut. Last summer, he appeared with Jon Tenney (''The Heiress'') in a full-fledged production of the play, written by Albom and playwright Jeffrey Hatcher, at the New York Stage and Film Company at Vassar College.

The two-week run was so successful that producers David Singer and Liz McCann decided to take the show to New York. There was talk, according to Albom, of opening ''Tuesdays With Morrie'' on Broadway. In that case, ''we would have had to have movie stars - at least that's what I was told,'' said Albom, who has written screenplays but had never worked before in theater.

''Every time they mentioned names of people [who could play the part], I said, 'I can't see them doing it better than Alvin.'

''We finally decided to do it off-Broadway because we didn't want to lose Alvin. Alvin's brilliant.

''He's just the right person, because you fall in love with him when you watch him onstage, just like you fell in love with Morrie when you walked into a room.''

This story ran on page E2 of the Boston Globe on 11/2/2002.