"Now 80 years old, Mr. Beliveau is currently undergoing active investigation and treatments," the team said in a statement. "As of today, and for the duration of his convalescence, Mr. Beliveau humbly asks everyone to respect his privacy and that of his family."
The native of Trois Rivieres, Quebec played with the Canadiens from 1950-71, notching 507 goals and 1,219 assists in 1,125 games. He also tallied 79 goals and 176 points in 162 playoff contests, retiring as the NHL's all-time leading playoff scorer.
Beliveau won 10 Stanley Cups during his playing career, and was elected to hockey's Hall of Fame in 1972. He added seven more titles as a Canadiens front office member.