Two dimensional echocardiographic criteria for bicuspid aortic valve recognition have greater specificity than previously proposed M-mode echocardiographic criteria. The potential clinical use of the two dimensional technique is, however, limited by the technical inability to image adequately the aortic valve leaflets in many patients. One hundred consecutive adult patients undergoing two dimensional echocardiography were prospectively studied. Valve cusp number could not be determined because of dense calcification in eight patients. A bicuspid aortic valve was diagnosed in a single subject. A parasternal short axis view disclosed three commissures (diastolic "Y" configuration) in only 26 patients. Technically adequate parasternal short axis imaging was more likely in younger patients and in non-smokers. In patients not successfully imaged from the parasternal approach, an anteriorly tilted apical four chamber view showed a diastolic "Y" configuration in an additional eight cases. Considering the high prevalence in our population of incomplete two dimensional echocardiographic aortic valve leaflet imaging, angiographic and/or pathological studies must be performed to establish the correlation between these incomplete echocardiographic patterns and aortic valve anatomy if two dimensional echocardiography is to have widespread application in the diagnosis of the congenital bicuspid aortic valve.