Despite recent advances in the perfection of cardiac valve prostheses, complications still bedevil the currently available models. To a degree, valve replacement is simply exchanging one disease for another. Mechanical prostheses are durable but associated with a high incidence of thrombo-embolic complications, while tissue valves are more resistant to thrombosis and thrombo-embolism but lack durability. The choice of prosthesis must be tailored to the individual patient's requirements, keeping in mind the social, economic and cultural characteristics of the population. Qualified support for conservative valve surgery (valvuloplasty) whenever reasonably possible would seem appropriate, even if it is later proved to have limited durability.