Chessex collapsed Friday evening while participating in a public discussion about a play that had been adapted from one of his novels, said Daniel von Siebenthal, mayor of the western Swiss city of Yverdon. He told local radio that the author died shortly afterward.
Chessex was among French-speaking Switzerland's leading writers and was honored in 1973 with the Prix Goncourt literary award for his novel "L'ogre" ("The Ogre"), a largely autobiographical account of a difficult father-son relationship. All previous winners had been French.
The novelist sparked heated debate this year with his last book, "A Jew Must Die," which recounted the 1942 killing of Jewish cattle trader Arthur Bloch in Chessex's hometown of Payerne. It was not warmly received by locals.
Chessex was born on March 1, 1934, the son of a high school director whose suicide in 1956 caused deep trauma for the budding writer.
He had already become known locally with his collection "Poems" as an 18-year-old, but broke through as a prose writer with a series of books in his 30s that made him popular in the French-speaking world.
His 1967 book "The Confession of Father Burg" debuted as a play on Thursday, the night before his collapse at Yverdon's city library.
Chessex was married three times and lived since the 1970s in Ropraz, near the border with France.
Funeral arrangements were not immediately known.