Mikhail Shatrov, 78, whose historical plays subjected Joseph Stalin and his legacy to withering scrutiny and signaled a new era of artistic freedom under Mikhail S. Gorbachev, died Sunday at his home in Moscow.

The cause was a heart attack, RIA Novosti news agency reported.

Under Stalin, Mr. Shatrov's father was executed and his mother exiled.

After Gorbachev assumed Soviet leadership in 1985 and ushered in liberalizing policies, Mr. Shatrov's works were staged without the cuts or revisions imposed by censors before.

In Dictatorship of Conscience, a group of journalists, each speaking in the guise of a historical figure, stages a mock trial of Vladimir Lenin.

A ringing affirmation of revolutionary idealism as embodied in Lenin, the play implicitly attacked the sclerotic, cynical system of the Brezhnev years and the lingering malign influence of Stalin.

"If you read my plays, you will see that all of them are in essence about one thing," Mr. Shatrov told the New York Times in 1988. "Stalin is a criminal of the kind the world has never had. He is not a communist for me, because if he is a communist, I have to leave the party immediately."

Mr. Shatrov was born Mikhail Filippovich Marshak in Moscow in 1932. On becoming a playwright he changed his last name to avoid confusion with an author of children's fiction and poetry, Samuil Y. Marshak.

He earned an engineering degree in 1956 but had begun publishing stories and plays, and with the cultural thaw under Nikita Khrushchev, a literary career opened up.

While skating on thin ice, Mr. Shatrov never became an outright dissident. He was a member of the Writers' Union and in 1983 was awarded the State Prize for the play Thus We Will Win.

- N.Y. Times News Service