Harper went on the 10-day IL on May 25 with a bruised left forearm. Prior to going on the injured list, the slugger had been in an 0-for-16 slump and was held out of the Phillies' lineup for the previous two games.
Before going on the IL, Harper was leading the team with a .489 slugging percentage, including 15 extra-base hits and seven home runs, but the slump has dropped his OPS to .884.
In a separate move, the Phillies placed closer Hector Neris on the paternity list.
Philadelphia has lost four of its past five games and is in the midst of an eight-game homestand that continues Saturday afternoon against the Washington Nationals.