The Carpentier-Edwards porcine bioprosthesis compares favorably to other value substitutes, with a low incidence of valve-related complications after up to 6 years' follow-up. From April, 1976, to February, 1978, 397 prostheses were implanted in 355 patients at the University of British Columbia and the Montreal Heart Institute: aortic valve replacement (AVR), 155; mitral valve replacement (MVR), 154; tricuspid valve replacement (TVR), five; multiple replacement (MR), 41 patients. Previous cardiac operations had been performed in 58 patients (16.3%). Concomitant cardiac procedures, including myocardial revascularization, were performed in 66 patients (18.5%). The 30 day mortality was 8.7% (31 patients (AVR, 4.5%; MVR 9.0%; TVR 20%; MR 21.9%). The cumulative follow-up was 1,367 patient-years (range 6 to 81 months, mean 51 months). The late mortality is 3.9% per patient-year (AVR 3.4%, MVR 3.6%, MR 6.3%). The long-term valve-related complication rates (expressed as percent per patient-year and number of events) are as follows; thromboembolism (AVR 1.1 [seven], MVR 1.7 [10], MR 3.2 [four]; prosthetic valve endocarditis (AVR 0.6 [four], MVR 0.3 [two], MR 1.6 [two]); primary tissue failure (AVR 0.16 [one], MVR 1.0 [six], MR 1.6 [two]); anticoagulant-related hemorrhage 0.07 (one); and reoperation (AVR 0.48 [three], MVR 1.32 [eight], MR 2.4 [three]). Actuarial survival rates at 6 years, including operative deaths, are as follows: AVR 81.4% +/- 5.6%, MVR 70.0% +/- 6.7%, and MR 52.1% +/- 12.5%. The overall survival rate was 74.0% +/- 4.5% at 6 years. The freedom from all valve-related complications at 72 months was 83.9% +/- 4.8%. The freedom from valve-related death was 97.3% +/- 1.8% at 72 months. The freedom from valve-related death and reoperation at 72 months was 91.5% +/- 3.8%, and the freedom from reoperation alone was 93.4% +/- 3.5%. There were no deaths due to reoperation for primary tissue failure. Performance to date with the Carpentier-Edwards porcine bioprosthesis has been excellent, with an evaluation interval extending from 60 to 81 months.