The group of 22 warm-blooded half-breed horses (6 stallions, 6 mares, and 10 geldings) and their riders (12 women and 10 men) who ended jumping competition for juniors, were selected for a study. The horses were aged from 7 to 17 years, while the riders were 15 to 18 years old. The saliva samples were collected before and after each jumping round. The cortisol concentration was determined by using an immunoassay method. The following factors were considered: horses’ sex, age, and breeds, riders’ sex and age as well. In riders, significant correlation was found in the group of younger juniors (15–16 years old) between the level of cortisol concentration before and after jumping round. High significant correlation coefficient was found due to influence of sex and age of horses on salivary cortisol concentration, but only for stallions and mares. Individual horses’ intensity of cortisol release in response to participation in jumping competition is found to vary greatly. Therefore, the salivary cortisol test seems to be a useful and efficient method to evaluate the horses’ responses to competitions including the influence of the rider.