The move is retroactive to Wednesday, the day after he pitched six innings and allowed four runs to the Chicago White Sox. Overall, Pelfrey, 29, has a 6.11 ERA over 14 starts this season.
The Twins have recalled LHP Pedro Hernandez from Triple-A Rochester to take Pelfrey's roster spot. Hernandez was up with the Twins earlier in the season, appearing in eight games, six of which were starts. He posted a 5.85 ERA over that span.
Over five games (four starts) for Rochester, Hernandez has a 4.50 ERA.
Hernandez is slated to start on Sunday for the Twins as they play the Cleveland Indians.