Implantation of the CarboMedics prosthetic heart valve began at the authors’ institution in November 1987 as part of a prospective multicenter trial set up by the manufacturer for an FDA application. A total of 132 patients (68 males, 64 females; median age 56 years (range 12-74 years)) received CarboMedics valves between November 1987 and August 1990. There were 69 aortic, 49 mitral, and 12 double (aortic + mitral) valve replacements. Two patients had isolated tricuspid valve replacement. After discharge, patients were examined in the outpatient clinic regularly until five years after surgery. Follow up was obtained prospectively with questionnaires to the patients’ general practitioner, and directly with telephone calls. Complete follow up data were available for 94% of the patients. Overall actuarial survival at 12 years was 62%. Actuarial freedom from embolism was 92%, and from anticoagulant-related bleeding 77%. No valve thrombosis was seen. Hemolysis, prosthetic valve dysfunction or structural deterioration were not seen. Over a 12-year time frame, the CarboMedics prosthetic heart valve has proven to be a highly reliable device with no structural failures, and a low incidence of valve-related complications.