Adam LaRoche hit two of Washington's six homers, Ian Desmond had four RBIs and the Nationals beat the Chicago Cubs 11-5 on Tuesday night.
LaRoche and Jayson Werth had four hits apiece for the NL East-leading Nationals, who opened a season-high 7½-game advantage in the division. Second-place Atlanta lost to Colorado 6-0.
Desmond, Jesus Flores, Tyler Moore and Ryan Zimmerman also went deep. The six home runs matched a team record.
Every Nationals starter had at least one hit.
Washington right-hander Edwin Jackson (9-9) allowed four runs and seven hits in 5 2-3 innings.