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Aim: Considering the fundamental role of parents' function and family dynamics including the importance role of family communication pattern on preventing early-onset substance use in children, the present study aimed to determine the correlation between family communication pattern and mothers' preventive behavioral intention regarding preventing early-onset substance use in children. Methods: This cross-sectional study was carried out among 234 Iranian mothers in Tehran who were randomly selected to participate voluntarily in the study. The participants filled out a self-administered questionnaire including I- demographic information; II- family-based behavioral intention regarding preventing early- onset substance use in children; and III- family communication pattern. Data were analyzed by the SPSS software (ver. 21.0) using Pearson's correlations, independent t-test, and ANOVA at 95% significant level. Findings: The results reported a correlation between conversation (r=0.509**& P≥0.001), conformity orientation (r= -0.150*& P=0.022) and behavioral intention; as well as between conversation conformity orientation (r= -0.382*& P≥0.001), and conversation (r=0.218**& P=0.001), conformity orientation (r= -0.105& P=0.108) and age. Conclusion: The findings suggest that to develop a preventive program, it will be useful to increase family communication pattern, specially conversation orientation to prevent the onset of substance use in children.