Background: Breast cancer is one of the most common types of cancer prevalent among women worldwide. Preventive behaviors such as early diagnosis through screening tests play an important role in prevention and control of the disease. This study aimed to determine the effects of educational intervention using a health belief model on breast cancer preventive behaviors. Method: This interventional study was conducted on 130 female employees of Zahedan University of Medical Sciences who were randomly divided into intervention and control groups. A questionnaire, made and validated by the researcher, was completed before and one month after training by the study subjects. Data were analysed using regression analysis, independent sample T-test, chi-square and Pearson’s correlation coefficient using the SPSS software 18. Result: There were significant changes in the training group, following educational intervention in the awareness construct and in some constructs of the model including perceived susceptibility, perceived benefits, and perceived barriers, as well as in practice compared to the control group (P < 0.05). Nevertheless, perceived barriers remained as the only predictor in the model, such that for every unit increase in this variable, the behavior score increased by 18%. Conclusion: The use of  educational intervention based on Health Belief Model had positive effect on knowledge of breast cancer preventive behaviors among participants.