7 patients with breast cancers during pregancy and loctatian seen at Korea University hospital during a 5 year period(1989-1993) were presented. They were found among 377 cases of breast cancers we experienced during the same period, for an incidence of 1.9%. Ages ranged from 25 to 31 years with an average of 31.9 years. A disproportionately long interval of average 79 days between the discovery of a lump in the breast by the patient and the actual diagnosis of the breast carcinoma was impressive. Three patients were diagnosed during the pregnancy and others after delivery. Modified radical mastectomy (Auchincloss) was performed for 6 pa- tients with operable breast cancer. One patient with locally advanced breast cancer was on preoperative chemotherapy, but she refused the therapy on the way. There were one stage I, two stage IIa, one stage IIb, two stage IIIa and one stage IIIb tumors. The literature was reviewed in a attempt to define most appropriate treatment for these oatients. Answers to traditional guestions about breast cancers during pregnancy and lactation are becoming less traditional. Radical mastectomy is almost as curative for pregnant patients with operable cancers as for others and presents little chance of fetal loss. Therapeutic abortion does not improve the chance for cure, nor does prophylactic castration. For inoperable or disseminated cancer, effective endocrine ablaiton or chemotherapy requires therapeutic abortion. Pregancy subsequent to mastectomy neither promotes nor diminishes the chance of continued maternal wellbeing. If age and study of disease are taken into account, pregnancy itself seems to have a neg- ligible influence on prognosis.