Improvement of materials, prosthetic function and perioperative treatment has led to positive results with regard to life expectancy, quality of life and complication rates in heart valve replacement. While mechanical valves are still associated with the risks of thromboembolism and anticoagulant bleeding, there is a continuing risk of early valve dysfunction in bioprostheses. We have preferred the latter during the last 8 years; however, certain disadvantages have become obvious during the follow-up of a group of 132 patients beyond the 6th postoperative year. Anticoagulant treatment has been withheld in some patients in spite of a clear indication while others have received coumadin in the absence of obvious reasons. Valve degeneration as discovered by echocardiography often was not recognized in time, resulting in a significant reoperative mortality. As a result the indication for biological valve replacement, especially in the mitral position, has become more restrictive in our hands.