A double from Chris Herrmann in the second scored Eduardo Escobar and Pedro Florimon to give the Twins the lead, 2-1. It was Herrmann's first two career RBI.
An inning later, Florimon put the Twins on top 4-1 with a two-run homer over the right field wall -- his third of the season.
Samuel Deduno started for the Twins, but he wasn't as effective against the Nationals as he had been in his previous two starts against the Tigers and Brewers.
Deduno allowed three runs on six hits and three walks, but he threw 94 pitches and was pulled after just five innings.
Anthony Swarzak came out to pitch the sixth inning, but he quickly gave up the one-run lead when ex-Twin Denard Span tripled to deep right, scoring Anthony Rendon to tie the game, 4-4.
The Nationals took the lead in the seventh on an RBI double from Ian Desmond off Swarzak.
The Twins had a chance to tie the game or take the lead in the ninth, but Josh Willingham fouled out with runners at first and third to end the game.
It's been a rollercoaster stretch of games for the Twins over the last month. They lost ten in a row, won eight of 10, and now have lost four of their last six.
At 27-33, they are back in fourth place in the American League Central division -- 7 1/2 games behind the first place Tigers.