Cardiovascular disease is the major cause of death worldwide. While since 1950s a major progress in cardiac valve repair and replacement has occurred, from about 280000 valve substitutes are now implanted each year, approximately half are mechanical valves. Flow dynamics of blood through the valves is the most important part of design. Material properties and fatigue must be considered too. The present book is a collection of some recent papers on computational modeling and design of MHVs focusing on hemodynamics and material properties. The principal function of heart and its valves’ malfunction will be introduced in the first chapter. Next some numerical investigation of blood flow through several prevalent MHVs will be considered in the second chapter and then materials and fatigue effect will be studied. In the last chapter, an optimization of the valve for thrombogenic performance and an optimal design of a fourth generation MHV through numerical modeling using CFD will be introduced. We hope that this book will serve as a valuable text for enthusiasts especially related researchers at graduate level and will cause to develop this attractive area of research.