The occurrence of malignancies during pregnancy has increased over the last decades. Risks of cancer surgery during pregnancy include spontaneous abortion and preterm labor. Radiation therapy especially during the first trimester generally is not offered because it poses high risks : teratogenecity, induction of childhood malignancies and hematologocal disorders. All chemotherapeutic agents used in the treatment of breast cancer are pregnancy category D, meaning that teratogenic effects have occurred in humans. We report a baby of a 33-year-old pregnant woman with breast cancer. She was treated with modified radical mastectomy one month before the pregnancy and full-dose adriamycin, cyclophosphamide and taxol since the first trimester, and 5,400 cGy of radiation therapy in the second trimester. The infant was delivered at 33+6 weeks of gestation and showed no evidence of malformation or abnormalities and developed normally until 8 months of corrected age.