Gaming is a natural process for the child, and with the play therapy technique used in this process, opportunities are offered to the child to express their problems and emotions by playing. Play therapy is used in many studies with children. The number of studies conducted on the effectiveness of play therapy in Turkey is increasing with each passing day. In this study, experimental graduate studies related to the play therapy education program from the past to the present (1987-2020) were examined and the results were brought together. A total number of 38 master's and 8 doctoral studies were reached in the YÖK (Council of Higher Education) thesis center related to the subject, but only 7 studies in accordance with the inclusion criteria were analyzed with meta-analysis method. While examining the postgraduate studies, care was taken toward the existence of an experimental and control group in which play therapy was applied. The studies in which play therapy was applied to the experimental group but not the control group were included in this study. In order to calculate the effect sizes, average (X), standard deviation (SS) and sample size (N) values from master's theses were processed in the Excel program. Later, CMA (Comprehensive Meta Analysis) statistical program was used for the analysis required for the study, "Hedges's g" was used to calculate the effect size and the Excel program was used for the collection-processing of the data. As a result of the research, it was found that the effect size of play therapy on children's behaviors has an excellent effect size. It was concluded that 5 of the studies included in the study were excellently effective, 1 was moderately effective, and 1 was broadly effective. These limited studies provide information that play therapy has a positive effect on children.