Introduction :Breast cancer is the most common malignancy among women - and second Leading cause of cancer mortality in most world wide countries. many studies indicate that Breast self examination ( BSE ), clinical breast examination ( eBE ) and mammography reduce mortality of breast cancer. This study assess effect of education of prevention on breast cancer on knowledge and belief of university. students (B.S) residing in fatemieh dormitory's of Tehran university by application heath belief model .

Methods: This study was quasi - experimental ( before -after) carried out on 99 university students. Sampling was a cluster multi stage random method. Selffadministered Questionnaire was prepared to collect the data. Paired T test, ANOVA, X2 test were used to analyze the data. The educational method applied was giving lectureecompanying Pamphlets and film and slide presentation. In this study Participants were between 20 - 25, 17.2 % of them had a positive family history of breast cancer, 12% of them were medical history of breast disease.

 Finding: While the mean number of the group in the pre test was 5.68(from total 22), it became 16.96 in posttest. paired T test indicated Mean of knowledge's and health belief score had a statistically significant difference between pretest and Posttest ( p < 0/0001 ) .

conclusion Education about prevention of breast cancer can promote knowledge and Attitude about screening measurement of breast cancer.