One thousand four hundred and twenty four patients with breast cancer were treated in our hospital from 1980 to 1993. The authors analysed the clinical date of this patients. The results showed that 1193 patients (84.4%) had menopause after 45 years old, 840 patients (59.4%) had menorrhea more than 30 years, 980 patients (80.5 %) had their first pregnancy after 25 years old, and 912 cases (74.9 %) had no history of breast feed. Breast cancer is related to genetic factors, other breast disease, mental factors and trace elements in human hair. The study of breast cancer and its relative factors can be expected to open a new road for the treatment and prevention of this disease.