Calgary Flames left wing Rene Bourque was suspended five games for elbowing Washington Capitals center Nicklas Backstrom in the head.
The incident occurred in the third period of Tuesday's game. Backstrom had just made a pass near center ice when Bourque elbowed him.
NHL disciplinarian Brendan Shanahan agreed the hit was not a "premeditated attempt to injure" but said Bourque's "reckless elbow to the head is indefensible."
Bourque was suspended two games last month for a hit from behind on Chicago Blackhawks defenseman Brent Seabrook.
Shanahan said that incident played a part in the length of the latest suspension.
The 30-year-old Bourque has 13 goals and three assists in 38 games this season.