['This study examines the clinical, echocardiographic, surgical, and pathologic features of patients who had heart valve operations for combined congenital bicuspid aortic valve and mitral regurgitation due to degenerative disease of the mitral valve.', 'A retrospective review of 1595 patients who had procedures for mitral regurgitation due to degenerative disease of the mitral valve and 1820 patients who had procedures for congenital bicuspid aortic valve disclosed 29 patients who had combined diseases.', 'The most common morphology of the bicuspid aortic valve was type 1 (fused right and left aortic cusps). Mitral regurgitation in 21 of 29 patients was caused by prolapse of the anterior leaflet, which was exceptionally large (mean height, 36.5 +/- 6.6 mm). Patients with prolapsed anterior leaflet of the mitral valve were younger (48 +/- 13 years vs 58 +/- 16 years, p = 0.01) and 95% were men. The bicuspid aortic valve was incompetent in 19 of 21, and the aortic annulus exceeded 30 mm in 20 of 21 patients.'] Is mitral regurgitation due to myxomatous degeneration combined with bicuspid aortic valve disease often due to prolapse of the anterior leaflet of the mitral valve?