Ondrusek was granted free agency after the season, and he signed a one-year contract with an option for 2018 in December.
This spring, Ondrusek was initially slowed by a sprained ankle, but he pitched in only two games. After his second appearance on March 6, Ondrusek complained of right elbow discomfort and he was examined by team doctors.
After the examination, Ondrusek requested a second opinion, and an appointment with orthopedist Dr. James Andrews was arranged for next Monday.
Ondrusek, a veteran of six major league seasons with Cincinnati and Baltimore, has a career 21-11 record with a 4.03 ERA.
Ondrusek's release leaves 39 players on the Orioles' 40-man roster.
Rich Dubroff is a contributor for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.