Tom Browning was a one-time All-Star and 1990 World Series champion with the Cincinnati Reds.
Retired pitcher was found unresponsive on his couch inside his Kentucky home.
No foul play is suspected in Browning's death, Boone County Sheriff's Office says.
In 1988, he threw the 12th perfect game in MLB history – a 1-0 defeat of the Los Angeles Dodgers.
In 1990, he was an All-Star and led the league in earned runs (107) and home runs allowed (32).
He finished his career in 1995 with the Kansas City Royals.