Given the importance of childhood disorders, the purpose of this study was to evaluate the effectiveness of individual play therapy on Oppositional-Defiant Disorder symptoms among children. A quasi-experimental research design type using a cluster sampling method was employed. The study sample included 30 girls and boys aged 6 to 10 years with Oppositional-Defiant Disorder symptoms referred to psychological consultation centres in the city of Ahvaz. Using simple random selection, the study sample was divided into an individual play therapy group (15 individuals) and a control group (15 individuals). The Child Behavior Checklist and Teacher Report Form (Achenbach & Rescolar, 2001) were used as measurement instruments. In addition, a clinical interview with parents was conducted to confirm the presence of the symptoms. The subjects were exposed to individual play therapy interventions during 8 sessions (each lasting 45 minutes) on a weekly basis and then evaluated in three stages including pre-intervention, post-intervention, and two months after the completion of sessions in a follow-up form. The SPSS software (version 18) and multivariate analysis of covariance (MANCOVA) were used for data analysis. The results of the multivariate analysis of covariance indicated that Oppositional-Defiant Disorder symptoms reported by parents and teachers in the individual play therapy group significantly decreased at the post-test stage compared with those in the control group. Furthermore, the results were consistent after the two-month follow-up evaluation. These findings showed that individual play therapy could reduce symptoms of Oppositional-Defiant Disorder among children. Therefore, it is recommended that therapists use this therapy in treating children affected with this disorder.
