Former bandmate Brad Fischetti (fih SHET' ee) tells The Associated Press that Cronin died in a Boston hospital on Wednesday.
The band is best known for its hit "Summer Girls."
Cronin had leukemia but Fischetti said he had beaten it. However, he suffered other health setbacks in recent years including a stroke.
Fischetti says he last saw Cronin last summer when the group performed for a reunion tour. He said there had been hope they'd all be able to perform together again this year.
