Our diploma theses are focused on horses participating in dressage competitions. In the literary review, we characterize this discipline, we describe its historical evolution, rules and we present some breeds mostly used in dressage competitions into the Czech Republic and abroad. Within the diploma theses, we are dealing with a statistical evaluation of the influence of age, color of coat, sex, breed and year of start on the dressage performance and on a number of participations in dressage competitions. Data from the Review of Sports Horses from 2010 and 2016 (published by the Czech Equestrian Federation) have been processed. Moreover, we have processed data from ranking of the best dressage horses for 2010 and 2016 which are also published by the Czech Equestrian Federation. The dressage performance has been evaluated on the basis of reached auxiliary points (AAP). We have evaluated statistically the influence of the same factors on the dressage performance at 200 best dressage horses around the world. These data are released by the Federation Equestre Internationale. Their performance has been rated on the basis of achieved points. We have processed and evaluated data using programme STATISTICA 2012. A sex factor from 2010 and a factor of a breed and of a year of the start in the both monitoring years have a statistically highly evaluated influence on the number of participations in dressage competitions. We have statistically evaluated the influence of the age, sex and breed factor on the dressage performance. It was alike at the most successful horses in the Czech Republic. Regarding the world rankings, only a factor of the start year has a statistically highly evaluated influence on the dressage performance. As for horses starting in the Czech Republic during the both monitoring years, the best results have been achieved by horses within the age of 13 to 16 years (3,33 PPB).A breed KWPN (4,84 PPB) and a group of stallions (3,44 PPB) have the statistically highly evaluated best dressage performance. The dressage performance in the Czech Republic is stable and it did not change remarkably from 2010 to 2016.