Breast cancer is the most frequent cancer type in women in the world. It is treated by surgery, chemotherapy, radiation therapy or in combination of these modalities. For the adjuvant treatment, tamoxifen is used widely. Pregnancy can occur during tamoxifen treatment in the premenoposal patients. But, there is no sufficient data safety of tamoxifen during pregnancy. So, here we presented the case using tamoxifen until 16 weeks of pregnancy. She was followed and delivered at the 38th weeks of pregnancy. No fetal anomalies have been observed in this case for three years. In the review of the literature addressing tamoxifen exposure during pregnancy, many studies are experimental and there are a few reports about pregnancy in human. Tamoxifen may be potentionally teratogenic, but frequently, this effect is not observed in human. So, tamoxifen exposure during pregnancy may not have a serious effect on the fetus.

Keywords: Tamoxifen, Pregnancy, Breast Cancer