We have reviewed 665 patients in whom the standard Hancock porcine bioprosthesis (HPB) was used for aortic (AVR = 173), mitral (MVR = 437), and mitral and aortic (MAVR = 55) valve replacement in the time interval from 1970 to 1983. After AVR, HPB-related deaths occurred in 24 patients (1.7% +/- 0.4% per patient-year); 11 had thromboembolic episodes (0.8% +/- 0.2% per patient-year), 6 hemorrhages related to anticoagulants (0.4% +/- 0.2% per patient-year), 9 endocarditis (0.7% +/- 0.2% per patient-year), 7 prosthetic leak (0.5% +/- 0.1% per patient-year), and 59 structural deterioration (4.3% +/- 0.6% per patient-year). At 16 years, actuarial survival is 40% +/- 6%, freedom from thromboembolic episodes 89% +/- 4%, from hemorrhages 90% +/- 5%, from endocarditis 94% +/- 2%, from prosthetic leak 95% +/- 2%, and from structural deterioration 36% +/- 6%. After MVR, HPB-related deaths occurred in 64 patients (1.6% +/- 0.2% per patient-year); 68 had thromboembolic episodes (1.7% +/- 0.2% per patient-year), 28 hemorrhages (0.7% +/- 0.1% per patient-year), 12 endocarditis (0.3% +/- 0.1% per patient-year), 9 prosthetic leak (0.2% +/- 0.1% per patient-year), and 158 structural deterioration (4.0% +/- 0.3% per patient-year). At 18 years, actuarial survival is 33% +/- 4%, freedom from thromboembolic episodes 57% +/- 13%, from hemorrhages 81% +/- 6%, from endocarditis 91% +/- 4%, from prosthetic leak 98% +/- 1%, and from structural deterioration 18% +/- 5%.(ABSTRACT TRUNCATED AT 250 WORDS)