The Toronto SPV bioprosthesis for aortic valve replacement has been prospectively evaluated in 100 patients, since March 1993. Intraoperative transoesophageal and postoperative transthoracic echocardiography were used to assess valve function. Follow-up was complete in 74 patients at 6 months and in 38 patients at 1 year. The average valve size implanted was 26.5 mm. Some 37 patients had additional coronary artery bypass grafting surgery. The hospital mortality rate was 4%. Non-structural valve dysfunction occurred in one patient and late endocarditis in another patient required operation. There were no other valve complications. None of the patients developed clinically relevant aortic valve incompetence during follow-up and there was a significant decrease in pressure gradients, increase in valve orifice areas and decrease in left ventricular hypertrophy.