The purpose of this study was to investigate the relationship between birth order and childbearing styles with obsessive-compulsive disorder among students of Tabriz Azad University. For this purpose, 380 students were selected by multi-stage cluster sampling. In order to collect information, the questionnaire of parenting styles (Robinson et al., 2001) and the multidimensional clinical personality questionnaire (2 million) were used. Regression analysis and one way ANOVA were used to analyze the data. The results showed that there is a significant relationship between the birth order and obsessive-compulsive disorder and also the parenting styles and obsessive-compulsive disorder among students. In addition, among the dimensions of childbearing styles, the authoritative parenting style has the most influence and effective parenting style, with the least impact on obsessive-compulsive disorder. Moreover, in the first offspring, there is the most likely occurrence of obsessive-compulsive disorder.
