Horses are companion animals, providing people as riders or spectators, with such pleasurable pursuits as racing, trotting, dressage etc. Racehorse populations provide examples of breeds, which have been selected over relatively longer period of time. The two breeds mostly used for gallop racing are Thoroughbred and American Quarter Horses. Among these two breeds, Thoroughbreds are used in longer races and American Quarter Horses are used in shorter races. The other type of racing is generally called harness racing. It is a form of racing in which the horses run in a specified gait (trot or pace). The main aim of this book is to compile all the published information on racing performance of horses. The first Chapter is the general introduction about the different gaits of the horses and breeds involved in horse racing. The second, third and fourth Chapters are devoted to the genetics of racing performance of Thoroughbred, American Quarter and Trotter Horses respectively. This book is addressed to broad audience and the information presented will provide valuable guidance to scientists and horse breeders involved in racing industry.