The occurrence of breast cancer during pregnancy is a rare clinical situation. However, if it is diagnosed, a multidisciplinary approach involving an obstetrician, a medical oncologist and a surgeon is needed. In this situation, breast cancer should be treated according to the same principles applied in nonpregnant patients. Termination of pregnancy does not improve survival. Decisions regarding abortion should be based on the desires of the patient and on therapeutic necessities. If required, surgery is always possible, but radiation therapy should be avoided because of the risk of fetal toxicity. Antineoplastic drug therapy, if indicated, is possible after the first trimester.