Background and Aim: Breast cancer remains the most common malignancy and major cause of death in women worldwide. Mammography is considered the most exact means to detect breast cancer in the earlier stage, which can reduce mortality of the disease. The current study aimed at evaluating the effects of an education program using the Theory of Planned Behavior on promoting mammography performance among employed women aged 35 years and over.

  Materials and Methods: This survey was a quasi-experimental study which evaluated the effectiveness of an education program to promote attitudinal factors associated with early detection of breast cancer in 220 women aged 35 years and over, who were working in Tehran pharmaceutical factories. Means of data collection was a questionnaire. The obtained data was analyzed by mean of SPSS statistical software (version 11.5) using non-parametrical tests (Chi-Square, Mann-Whitney, McNemar’s, Wilcoxon) and P<0.05 was taken as the significant level.

  Results: It was found that the mean score of knowledge, attitude, perceived behavioral control, intention and behavior in women regarding mammography in the case group significantly increased and the observed difference in the control group was not significant.

  Conclusion: Application of the Theory of Planned Behavior has an acceptable influence on promoting mammography behavior. It is, therefore, recommended that education programs apply the theory to promote mammography behavior (in women).