Ruff and the Sabres have struggled this season, going 6-10-1 and ranking 13th in the Eastern Conference.
"This is professional sports. (Lindy) understood it. He was extremely professional," said Sabres GM Darcy Regier. "It's a tough day, it really is."
Ruff, the all-time winningest coach in Sabres history, was in his 15th season behind the Buffalo bench (16th, if you include the 2004-05 NHL lockout). He was originally hired as the 15th head coach in team history on July 21, 1997.
In 2005-06, Ruff was honored by the NHL with the Jack Adams Award as the league's Coach of the Year. Ruff joined Ted Nolan (1997) as the only other head coach in team history to receive the honor.