The Purpose of this research was to investigate parental monitoring role and affiliation with deviant peers in high risk behavior. The design of the current study involves correlation using structural equation modeling. The population of the current study involve all male and female adolescent in Tehran high school from which 1241 were selected through cluster sampling. To collect the data, different scales such as Iran’s adolescent risk-taking scales, parental monitoring scales and affiliation with delinquent peers were used. The data were analyzed using correlation statistical indices, independent T and structural equation modeling through SPSS and LISRER. The obtained results showed that there was a significant difference between girls and boys in high risk behavior, parental monitoring and affiliation with delinquent peers. Moreover, parental monitoring through affiliation with delinquent peers had a significant effect on high risk behavior. The mediating model can explain 0.55 high risk behavior variance. It's highly influential to pay attention to the parental monitoring role in decreasing affiliation with delinquent peers as well as decreasing the high risk behavior by adolescents. .