Objective: The study designed to evaluate the effectiveness of parent-based Pivotal Response Treatment (PRT) on improvement of children with autism. Methods: Twenty children with their parents were recruited through available sampling and randomly assigned to two control and experimental groups. Research design was pretest- post-test design with control group and follow-up. The experimental group was trained in PRT during three months. Childhood Autism Rating Scale (CARS) and Autism Treatment Evaluation Checklist (ATEC) were used as instruments for measuring improvement of children’s autistic features. Results: Results showed that PRT was significantly effective in decreasing symptoms of autism. Also, in speech/language, communication and sociability subtests significant result was observed (P<0.05) whereas in sensory/cognitive awareness and Health/Physical/Behavior subtests there were not any statistically significant results. Conclusion: According to benefits of parental intervention in treatment and importance of increasing therapy sessions for children with autism, it is recommended that this therapy method in conjunction with conventional methods is offered to parents of children with autism specially mothers.