From January 1981 through December 1991, 1120 consecutive aortic valves were surgically explanted and their gross anatomy and histology studied at our university. Rheumatic disease (65%), dystrophic calcific valvular disease (23%), noninflammatory disease of the aortic root and/or floppy aortic valve (6.3%), and endocarditis (5.4%) were the causes of valve dysfunction. Among the total population the male sex predominated. The male to female ratio was 2.4 in the group with dystrophic calcific valvular disease and 1.6 in the group with bacterial endocarditis. The mean age was 37 ± 7.5 years in the group with non-inflammatory disease of the aortic root and/or aortic cusps. In the group with dystrophic calcific valvular disease, the mean age was 62 ± 6.3 years. Among the 1120 patients, 717 (64.03%) underwent surgery for aortic stenotic-incompetence, 250 (22.25%) for isolated aortic stenosis, and 153 (13.72%) for isolated aortic incompetence. In 449 cases (40.13%) a mitral pathology was associated. Chronic rheumatic aortic disease usually caused stenotic insufficiency (92.8%). Dystrophic calcific aortic disease caused pure stenosis in 84.8% of the cases. Among these, 46 patients (18.4%) had a congenitally bicuspidal aortic valve. Pure aortic incompetence was caused by noninflammatory aortic root and/or cusp disease in 44% of patients, infective endocarditis in 40%, and rheumatic disease in 16%. Patients with noninflammatory aortic root and/or cusp disease were divided into three groups: 29 patients with aortic root dilatation and normal cusps, 25 patients with aortic root dilatation and mixomatous infiltration of aortic cusps (floppy aortic valve), and 15 patients with floppy aortic valve and normal aortic root. Aortic incompetence was caused by cusp retraction caused by chronic rheumatic disease, cusp perforation or tears caused by infective endocarditis, and cusp prolapse for floppy aortic valve. Cusp diastasis has been the cause of aortic incompetence in patients with dilated aortic root. In patient with floppy aortic valve caused by the fibrous lamina disarray, the cusps prolapsed toward the left ventricle, causing valve regurgitation.