In order to evaluate our clinical results with the use of the Biocor prosthesis, a total of 1,101 patients were studied. Follow-up was from 1 to 96 months (mean 48); cumulative follow-up in the aortic group (385 patients) was 1,230 patient years and in the mitral group (716 patients) 3,018 patient years. Mitral patients had 102 late complications (14.24%), and aortic patients had 51 (13.2%). A total of 220 patients were under 20 years of age (176 mitral, 44 aortic). Intrinsic valve failure in this subgroup was found in 43% of mitral patients and 29% of aortic patients. Prosthetic endocarditis was more frequent in the aortic group (45%) than in the mitral group (29.9%). Sixty-two patients were reoperated, with a hospital mortality of 12.6%. Reoperation was more frequent in the mitral group and in patients under 20 years of age. The actuarial curve free mortality related to the bioprosthesis was 97.1% (32 patients). At the 8-year follow-up, 96.9% of the aortic versus 95.2% of the mitral group were free of valve dysfunction, and the majority were in Classes I or II of the New York Heart Association (NYHA) classification. The incidence of reoperation, although significant, is acceptable, especially since the bioprosthesis offers a safer alternative than mechanical prostheses followed for similar periods. Analysis of our results suggests the need for continued research for an ideal bioprosthesis.