Nationals activate Ryan Zimmerman
Rookie third baseman Anthon Rendon was optioned to Double-A Harrisburg of the Eastern League.
Zimmerman had been on the disabled list since April 18 with a strained left hamstring and the Nationals were 6-8 in his absence.
He played in one game for high Class A Potomac on an injury rehabilitation assignment, going 0 for 3 on Wednesday against Carolina.
''I really only needed to play one game just to test the hamstring, make sure I could run out a ground ball or charge a slow roller,'' Zimmerman said. ''I only missed three days of (batting practice), so it wasn't like I needed a lot of at-bats to get my timing back.''
Zimmerman went into Friday' game with a .226 batting average, 61 points below his .287 career mark. He had one home run in 15 games but his 11 RBI were tied with Bryce Harper for the team lead.
Rendon, the Nationals' first-round draft pick in 2011, hit .240 with one RBI in eight games in his first major league stint.