OBJECTIVE Clinical experience with the Omnicarbon mechanical valve implanted in the aortic position is reported in this retrospective survey. METHODS A total of 110 patients (mean age 56 years) undergoing isolated aortic valve replacement with Omnicarbon mechanical prostheses at the authors' institution between November 1991 and October 2000 was included. Follow was available in 94.5% of patients (mean follow up 4 years per patient; total follow up was 415 patient-years (pt-yr)). RESULTS Hospital mortality was 3.6%. There were no instances of valve thrombosis or structural failure. The incidence of valve-related complications (linearized rates in events per 100 pt-yr/actuarial freedom at 9 years, in %) was: valve-related mortality 2.4+/-0.7 / 80.3+/-8.0; non-structural failure 0.7+/-0.4 / 93.8+/-4.2; thromboembolism 0.2+/-0.2 / 99.0+/-1.0; anticoagulant-related hemorrhage 0.9+/-0.5 / 93.7+/-3.3; prosthetic valve endocarditis 0.2+/-0.2 / 99.0+/-1.0; and reoperation 0.7+/-0.4 / 93.8+/-4.2. CONCLUSIONS In the authors' experience the Omnicarbon mechanical prosthesis provides a good clinical performance for up to nine years in the aortic position.