Most studies concerning aortic valve structure in patients having aortic valve replacement have utilized the valve structure (unicuspid, bicuspid, tricuspid) as that called by the cardiac surgeon performing the operation. We determined valve structure of 744 operatively excised stenotic aortic valves submitted to the surgical pathology laboratory of a single hospital over a 6-year period and then compared valve structure determined by a single cardiac pathologist (WCR) with that recorded in the operative report dictated by the operating surgeon. Compared with that determined from examination of the operatively excised valve by the cardiac pathologist, valve structure determined at operation was congruous in 59% (440 of 744 patients), incongruous in 20% (152 of 744), of uncertain structure in 1% (9 of 744), and not mentioned in 19% (143 of 744). Valve structure was virtually always congruous (278 of 280 cases, 99%) in patients with 3-cuspid valves, less so with bicuspid valves (156 of 280, 56%), and infrequently so with unicuspid valves (6 of 41, 15%). In conclusion, in patients having isolated aortic valve replacement for aortic valve stenosis, the structure of the valve by the operating surgeon was similar (99%) to that described by 1 of us (WCR) when a 3-cuspid aortic valve was excised, but less so when a congenitally unicuspid (15%) or bicuspid (56%) valve was excised.