Introduction: The use of horses in therapy has a fairly long history. There are many references to the therapeutic benefits of this activity. Such therapies have been undergoing a boom internationally in recent years. However scientific research into the effective use of this activity in children with autism is still in the early stages of development. Method: The impact of a therapeutic horse-riding program on a set of psychosocial variables in a group of 8 autism spectrum disorder subjects of 7 to 16 years in age is evaluated. The study design was quasi-experimental, test-retest, with two groups -- experimental and control. The measurement instruments were the "Behavior Assessment System for Children" (BASC), and a quality-of-life questionnaire based on a standard model used in mental health contexts. The treatment program comprised twenty-four 45-minute sessions. Results: The results show significant differences in some of the quality-of-life indicators and there were lower levels of aggressiveness (BASC). Discussion and conclusions: The horse riding is particularly well matched to the specific characteristics of persons with autism, since it is based on an individual activity but at the same time brings into play multiple interactions in a context which is more structured and less chaotic than other team sports.