Latendresse had the fourth two-goal game of his NHL career - the second this month. He has nine goals this season.
Latendresse's second goal gave the Canadiens a 3-1 lead with 2:54 left in the second period. His slap shot from about 30 feet beat goalie Olie Kolzig.
The Capitals peppered Cristobal Huet, who started his first game since Dec. 1, with 37 shots. The Canadiens had 21 against Kolzig, but scored on five.
The Canadiens took a 2-0 lead at 6:33 of the second period when Tomas Plekanec scored .
Nicklas Backstrom scored his sixth goal as the Capitals cut their deficit to 2-1 with a power-play goal at 9:10 of the second.