ZURICH -- Erich Leinsdorf, 81, a leading conductor of U.S. and other orchestras who was known for reviving neglected music and exploring new works, died of cancer Sept. 11 at a hospital here. He lived in Zurich and Sarasota, Fla.

His demanding and abrasive manner sometimes put him at odds with singers and other musicians. He was active in conducting until January, when he performed with the New York Philharmonic.

He was known not only for his familiarity with Mozart -- he recorded all his symphonies for RCA -- but also for exploring new works and reviving music he thought had been unjustly ignored.

Among major works he introduced was British composer Benjamin Britten's "War Requiem."

Mr. Leinsdorf was born in Vienna, where he studied piano and conducting and began pursuing his conducting career in the 1930s. Even before the Nazi annexation of Austria, Mr. Leinsdorf was having problems getting a prominent conducting post in Vienna because he was Jewish.

He had caught the attention of Arturo Toscanini, whom he assisted at the Salzburg Festival. Toscanini recommended him to the Metropolitan Opera in New York in 1937. Mr. Leinsdorf made his American conducting debut with the Met in a 1938 performance of Wagner's "Die Walkure."

From 1939 to 1943, he was in charge of the Met's German repertory, then took over briefly as music director of the Cleveland Orchestra. He served from 1947 to 1956 as music director of the Rochester, N.Y., Philharmonic, followed in 1956 by a year as director of the New York City Opera.

He eventually took over as music director of the Boston Symphony Orchestra, perhaps his most prestigious post and one he held from 1962 to 1969. He spent his later years as guest conductor of major orchestras.

Among his major recent appearances was an acclaimed performance of Mozart's "Requiem" by the New York Philharmonic in December 1991 to commemorate the 200th anniversary of the composer's death.

He once said he saw conducting as "more or less like coaching a team in sports, plus taking part in the game."

"You have to program yourself to live a quiet life and not bum around," he said. "My wife and I don't stay out late. We have a very nice set of friends, live on a sensible diet."

He was the author of "The Composer's Advocate," a highly regarded book on conducting, and his autobiography, "Cadenza -- A Musical Career."

His first marriage, to the former Anne Frohnknecht, ended in divorce.

Survivors include his wife of 25 years, Vera Graf Leinsdorf of Zurich and Sarasota; five children from his first marriage; and 10 grandchildren.