His wife, Pearl, says Radnitz died Sunday from complications of a stroke he suffered 14 years ago.
Radnitz became known for developing family movies, starting in 1959 with "A Dog of Flanders." Many were based on children's literature, including "Misty" in 1961. He went on to produce nearly a dozen such films, some in partnership with toy maker Mattel.
In 1973, the Los Angeles Times called Radnitz "the only successful American maker of children's films outside the gates of Walt Disney films." Radnitz is survived by his wife of 23 years.