The aim of our study was to investigate the effects of a small therapeutic animal (TA, guinea pig) on the social behavior of nine autistic children. The social contacts of the autistic children were evaluated by a descriptive method of direct observation that was performed without (in period one) and with (in period two) the presence of a TA. In period one, contacts with an unfamiliar person (UP) and acquaintances (A) were registered; in period two, contacts with the acquaintances and the TA were registered. The frequency of contacts of autistic children with their acquaintances significantly increased in the presence of the TA (P < 0.001). The frequency of contacts with the TA was significantly higher than the frequency of contacts with the UP (P < 0.001). The form of the autistic children’s contacts with A, with the UP, and with the TA was individually dependent, and the presence of the TA changed the characteristics of contacts with A. Our results indicate that the presence of a small TA can positively influence the quantity and quality of the social behavior of autistic children and that the characteristics of social contacts were dependent on the individual.