This 37-year-old woman was diagnosed with breast cancer during pregnancy. After multidisciplinary meeting, she was referred to our department for an FDG PET/CT for staging, and chemotherapy with weekly infusion of paclitaxel was initiated before childbirth. We estimated the fetal dose from the PET/CT procedure, and our results show that, if deemed necessary, this examination can reasonably be performed during pregnancy. The patient gave birth vaginally at term to an apparently healthy girl.