Hegyes was taken to the hospital from his New Jersey home in full cardiac arrest on Thursday.
Doctors pronounced him dead shortly after his arrival.
His claim to fame was playing wise-cracking Jewish Puerto Rican high schooler Juan Epstein alongside John Travolta.
The TV series followed a teacher who returns to the inner-city New York school of his youth to teach a group of irreverent remedial students nicknamed the "Sweathogs."
The show's theme song, performed by John Sebastian, became a pop hit.
Hegyes also appeared on many other TV series, including "Cagney & Lacey."
He was born in Perth Amboy and grew up in Metuchen, the eldest child of a Hungarian father and Italian mother.
The Associated Press contributed to this report.