DeRosa has been out since May 9 with an inflamed nerve in the wrist. He went on a minor league rehabilitation stint this month but it bothered him again, forcing him back to a doctor.
The date for the surgery by hand specialist Dr. Thomas Graham has not been set.
DeRosa had left wrist surgery following last season but that problem was in a different area of the wrist.
DeRosa, who signed a $12 million, two-year deal with San Francisco last winter, finished with one homer and 10 RBIs in 26 games in his first season with the Giants.
Mourinho expects successSan Francisco Giants outfielder Mark DeRosa to have more tests on left wrist
