He had been suffering from Alzheimer's disease and died at his San Francisco home, his nephew and longtime business partner Paul said, reported Variety.
Zaentz began his career as a music producer, before turning to filmmaking at age 50.
He won the Best Picture Academy Awards in 1976 for 'One Flew Over the Cuckoo's Nest', in 1985 for 'Amadeus' and in 1997 for 'The English Patient'.
Zaentz was not prolific as a movie producer, instead specialised in complex literary adaptations that Hollywood studios generally found too intricate to put on film.
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He also brought out the 1986 Harrison Ford drama 'The Mosquito Coast'; 1998's acclaimed 'The Unbearable Lightness of Being', which co-starred 'The English Patient' Oscar winner Juliette Binoche; and 1991's 'At Play in the Fields of the Lord', a critical and commercial flop despite a cast that included Kathy Bates, Tom Berenger and John Lithgow.
After the war, Zaentz attended business college and moved to San Francisco, where he worked for a small record distributor and later joined jazz producer Norman Granz, working on recordings and concerts.
Zaentz entered the movie business after growing bored with his successful recording-industry career, which included the Fantasy Records label he bought in 1967.
Zaentz is survived by four children: Dorian, Joshua, Athena, and Jonnie; seven grandchildren, and his nephew.