Objective To study the incidence andassociated lesions of quadricuspid aortic valves (QAV) and to explore the echocardiographic diagnostic value and outcomes of surgicaltreatment. Methods Over a 3-year period, 92 656 patients were studied by TTE. Congenital quadricuspid aortic valve deformity wasdiagnosed by TTE and real time three-dimensional echocardiography. The morphologic changes, echoes, opening and closing of QAVand blood flow dynamics were observed by Philips SONOS-7500 color ultrasound system. Results Diagnosis of QAV was made in 23patients (0.248‰). Their ages were 19～83 years, including 11 male, and 12 female. One patient showed normal QAV function, 5had grade Ⅱ aortic regurgitation, 1 had grade Ⅱ～Ⅲ aortic regurgitation,2 patient Ⅲ, 10 patients Ⅲ～Ⅳ,4 patients Ⅳ. 9 QAVpatients underwent aortic valve replacement with surgical confirmation of the valve morphology. No stenosis was found. Associated le-sions were mitral valve prolapse and tricuspid insufficiency. Conclusion QAV is rare, most of them may present with pure aortic re-gurgitation without stenosis. Severe aortic insufficiency requires surgical treatment.