Introduction: Given the important role of family in shaping human behavior, the current research has been conducted with the aim of identifying the family characteristics of individuals with risky sexual behaviors.
 Materials and Methods: In this correlative study the statistical population included women with risky and extramarital sexual behaviors. 104 women were selected through available sampling method in 2010-11 in Tehran. Data collection tools included: AIDS Risk Assessment Questionnaire to assess risky behavior and related factors and the Risky Sexual Behavior Questionnaire and Family demographic questionnaire. SPSS software, t-test, analysis of variance, and correlation coefficient were used for data analysis.
 Results:Results from studying the family factors and variables related to the degree of risky sexual behaviors in the study group shows that residential situations, occupational conditions, living conditions, parents' living status, and the degree of intimacy in the family has a significant negative relationship with risky sexual behaviors (P<0.05). There is a positive correlation (P<0.05) between history of abuse by family members and the number of risky sexual behaviors. There is no significant correlation between marital status, educational status, and parents' living status with risky sexual behaviors (P>0.05).
 Conclusion: Based on the results about the important role of family in the risky sexual behaviors, and also the increasing rate of these behaviors in our society, attention to the role of family is necessary for its prevention.