Since 2004, the Ministry of Agriculture, Fisheries and Food of Spain organize the Young Horses Performance Selection Tests, for different disciplines, like Show Jumping. Only young animals participate in these events (4 to 6 years old). With the data collected during 3 years (4.441 participations from 87 different horses), we have analyzed the environmental factors that influence the performance results of the animal in these type of tests. A Proc MIXED model from SAS was used, including final penalizations and transformed ranking as dependent variables. 14 factors, related to the animal (age, sex?), the competition location and the racetrack conditions, the climatologic conditions, the training level and the stress level of the animal, were analyzed before the competition. The rider and the father were included in the model as random factors, and the participation order as the covariate. Although most of the factors and their combinations were significant, they explained a very low variance (from 0.07% to 1.78%), excluding the age (2.40%), the father effect (9.25%) and the rider (8.28%).