In order to determine the long‐term results of aortic valve replacement with the Smeloff‐Cutter prosthesis, the fate of 134 of 139 (96%) consecutive patients was determined one to 12 years after operation. The mean age at operation was 54 years (range 18 to 76 years). Aortic stenosis was the dominant lesion in 77 patients (55%), aortic regurgitation in 36 patients (26%), and 22 (15%) had both aortic stenosis and regurgitation. In addition to aortic valve replacement, 25 patients (18%) had coronary artery bypass, seven (5%) had mitral commis‐surotomy, and four (4%) had other procedures. Preoperative status by NYHA Class was: Class I … 3 patients (2%); Class II … 36 (26%); Class III … 67 (48%); Class IV … 33 (24%). Perioperative (30‐day) mortality was 7% (10/139). Functional improvement was obtained in all postoperative survivors with 86 (70%) in NYHA Class I,28 (23%) in Class II, and nine (7%) in Class III. A perivalvular leak developed in one patient and subacute bacterial endocarditis in two (2%). There were no cases of prosthesis failure or haemolysis. Actuarial long‐term survival was 85% at five years, 75% at eight years. Thromboembolism occurred in eight patients (6%). The incidence of thromboembolism per 100 patient years for patients receiving no anticoagulants was 5·5; taking warfarin 2·4; and taking antiplatelet agents 2·7. Major thromboembolism was uncommon in patients taking warfarin (0·9 episodes per 100 patient years.)The study confirms that the Smeloff‐Cutter aortic valve prosthesis is mechanically durable, has good long‐term haemodynamic performance, and carries a low incidence of thromboembolism even in patients not