Background : After lung cancer, breast cancer is the second cause of mortality among women. Although the prevalence of this disease has been increased, but the rate of mortality has not been changed during last three decades, this may be due to early diagnosis at the first stage of disease .

  Objective : To determine risk factors of breast cancer in women.

  Design : It was a case- control study. Personal, familial, fertile characteristics and stressful life events in women with breast cancer were determined and compared with non cancerous women (control group).

  Samples : One hundred twenty patients with breast cancer were selected randomly and compared with the same number of healthy women..

  Results : Among personal factors, mariatal status (p=0.006) history of benign breast tumor (p=0.028), breast stroke (p=0.031), excessive chest x-ray (p=0.045), sport activities (p=0.002), consumption of olive oil (p=0.054). consumption of white meat (p=0.01), consumption of fresh fruit and vegetables (p=0.0006) were significantly related with breast cancer. Among familial factors, history of breast cancer in first class family members (p=0.023) were significantly associated with cancer of breast. There was also a relation between breast cancer and stressful life events (p=0.000). Among fertility factors, there was a relation between breast cancer and number of abortion (p=0.046), and also kind of abortion (p=0.053).

  Conclusion : In this study, risk factors of breast cancer were mariatal status, benign breast tumor, history of breast stroke, frequent chest x-ray, physical exercises, nutritional conditions, history of breast cancer in first class family, father's age at the time of case birth, number and kind of abortion and finally stressful life events. Unfortunately some of this factors are not preventable organization in order to make people aware of risk factors and ways of their prevention.