OBJECTIVE We retrospectively examined the outcomes of 264 patients who underwent consecutive Omnicarbon valve implantation surgery between April 1985 and May 1995. METHODS At the time of surgery, patients who received this mechanical prosthesis averaged 57+/-11 years of age. Omnicarbon valves were placed in the aortic position in 36% of the cases, in the mitral position in 44%, and in both positions in 20%. Follow-up was carefully performed, with most patients undergoing physical examination at our clinic. While taking the case history, cardiac physicians specifically questioned the patient about valve-related complications. RESULTS Accumulated total patient-years is 1291, with a mean follow-up time of 5.4 years. Survival at 10 years is 79.4+/-3.9%, including all causes of death and early mortality. Complications recorded during the 11-year study include: thromboembolism (0.1%), hemorrhage (0.4%), endocarditis (0.2%), and nonstructural failure (1.2%). No hemolytic anemia, valve thrombosis, or structural failure was detected during this long-term experience. Functional capability of these patients was subjectively assessed by the NYHA classification system. With follow-up time averaging over 5 years, 97% of our Omnicarbon valve patients are in NYHA I or II. CONCLUSIONS The Omnicarbon mechanical prosthesis provides a good clinical performance for up to 10 years in both the aortic and mitral positions. Results indicated a low incidence of thromboembolism and of hemorrhagic complications.