Parker was examined Monday in Gulf Breeze, Fla., by Dr. James Andrews, who repaired his elbow on Oct. 28, 2009, when Parker was with Arizona. Parker is to have surgery again on March 25.
Parker had a 10.61 ERA in three spring training starts.
He becomes the latest pitcher who needs a ligament replaced, joining Arizona's Patrick Corbin. Atlanta pitchers Kris Medlen and Brandon Beachy also were being examined by Andrews on Monday and might need season-ending elbow surgery.
Parker's surgery clears the way for Jesse Chavez and Tommy Milone to join Oakland's starting rotation.
Oakland left-hander Scott Kazmir was scratched from his scheduled start Monday against the Chicago Cubs due to left triceps stiffness. But that injury isn't thought to be serious.