Objective: The present study aimed to study the effectiveness of equine-assisted therapy (EAT) on the symptoms of children with Autism spectrum disorders. Method: The study population included children who were diagnosed as autistic in a rehabilitation center in Tabriz City, Iran during 2017-2018. For this purpose, using a quasiexperimental research design with pre-test and posttest and a control group, 20 children were randomly assigned into two groups (one experimental group and one control group). These two groups of children had been diagnosed with behavioral problems using Gilliam Autism Rating Scale (GARS). The experimental group was trained by horses and the control group did not receive any training. The data were analyzed using multivariate analysis of covariance (MANCOVA). Results: The results showed that EAT was not effective to improve the communication skills of children with Autism disorder; however, it increased the social skills of children with Autism disorder with an effect of 0.37. EAT influenced the stereotyped behaviors of children with an effect of 0.38. Conclusion: Due to the fact that autistic children often prefer interactions with objects over interactions with people and respond positively to the presence of non-human living creatures. the positive effects of this treatment on children with autism spectrum can be explained.