Bioprosthetic valve thrombosis is an uncommon complication. We report two young women with prior uncomplicated percutaneous pulmonary valve replacement (Melody®, Medtronic, Inc. Minneapolis, MN) who later developed symptomatic pulmonary emboli and pulmonary valve dysfunction without evidence of infection. Thrombophilia risk factors included oral contraceptive use and mild thrombophilia. Both experienced recovery of valve function following anticoagulation. Acute changes in Melody® valve function should prompt a thorough investigation for and treatment of potential thrombotic causes. © 2016 Wiley Periodicals, Inc.