Lee Strasberg, 80, who exerted a profound influence on the American theater through his teaching and advocacy of "the method" school of acting, died yesterday at St. Luke's-Roosevelt Hospital in New York City following a heart attack.

From 1948 until his death, Mr. Strasberg was the artistic director of the Actors Studio, Inc. His students there included Marlon Brando, Ellen Burstyn, Al Pacino, Eli Wallach, George Peppard, Ben Gazzara, Shelley Winters, Joanne Woodward, Paul Newman, Jack Nicholson, Dustin Hoffman, Arthur Penn, Cliff Robertson, Eva Marie Saint, Julie Harris, Carroll O'Connor, Lee J. Cobb and Marilyn Monroe.

On Mr. Strasberg's 75th birthday, it was estimated that actors and actresses trained by him had won 24 Oscars and received nominations for 108 others.

Apart from his celebrity as a teacher, Mr. Strasberg was also a successful actor and director. He made his film debut in 1974 as Hyman Roth, an aging syndicate boss in "The Godfather: Part II." He appeared with George Burns and Art Carney in a recent film about a trio of elderly bank robbers, "Going in Style," which appeared on television earlier this week. On Sunday night, he appeared at the "Night of 100 Stars" production at Radio City Music Hall.

Satisfying as they were, Mr. Strasberg's more recent forays before the klieg lights and the footlights were grace notes near the end of a life spent in the theater. The unifying principle of that life was "the method." It has been hailed as the quintessence of realistic American acting and derided as the "torn-T-shirt-school" of the theater.

Konstantin Stanislavski, the founder of the Moscow Art Theater, is credited with creating "the method." Mr. Strasberg, who studied briefly with Stanislavski and more extensively with earlier disciples of the Russian, is regarded as its master. In an interview in 1976, he described it in these terms:

"Our procedure is an attempt to lead each actor to solve each acting problem in accord with the nature of his own individual material -- as revealed to us by our understanding of this modern knowledge -- so that it is possible, technically speaking, for that actor to become a completely functioning instrument.

"The Stanislavski method is not as new as we commonly think. The work that we do is nothing but the sum total of the experiences of many great actors of the past, of the records and statements they have left and of what we have seen in our own experience. What Stanislavski tried to do was to make this material available to the young actor so that he doesn't have to go through 25 or 30 years of grueling experience to find these things for himself."

What this became in practice was an effort by actors to "feel" their parts as well as think their way through them. Students were encouraged to improvise as a way of getting inside their roles. Performances should emerge from emotion and disposition rather than external effects and mannerisms. According to Mr. Strasberg, "a career must develop in public, but one's talents must grow only in silence." The Actors Studio was designed to provide the silence.

Such was Mr. Strasberg's success that Elia Kazan, a founder of Actors Studio, wrote in The New York Herald Tribune in 1958: "Mr. Strasberg is a fine director, but first of all he is that extraordinary and unique phenomenon: a born teacher . . . our whole theater would have been less vital and less ambitious without the influence of this one man who has given so quietly and so unceasingly to so many people, because it is his nature to study and to think and to teach."

Mr. Strasberg was born in Budanov, then in Austria-Hungary and now in the Soviet Union. He came to the United States with his family in 1909 and grew up in New York City, where his interest in the theater led him to play in skits at the Chrystie Street Settlement House. His first job was in a factory that made theatrical wigs. He studied at the American Laboratory Theater, where both of his teachers, Richard Boleslavski and Maria Ouspenskaya, had been students of Stanislavski.

In the early 1920s, Mr. Strasberg joined the Theater Guild, where he met Harold Clurman and Cheryl Crawford. In the 1930s, the three founded the Group Theater to develop Stanislavski's ideas and to put on plays that deserved to be seen even though commercial success eluded them.

Mr. Strasberg spent most of the 1940s in Hollywood, an interlude that he later described as "an unfruitful but nonetheless educational experience." In 1947, the Actors Studio was started by Elia Kazan and Cheryl Crawford with Robert Lewis as director. A year later, Mr. Strasberg took over as artistic director.

Mr. Strasberg's first wife, Nora Z. Krecaun, died. In 1934, he married Paula Miller, an actress who was long associated with his work. She died in 1966.

Survivors include his wife, the former Anna Mizrahii, and their two children, David and Adam, all of New York City, and two children by his second marriage, actress Susan Strasberg, and John.