This chapter reviews the current information and controversies regarding different aspects of the administration of chemotherapy during pregnancy. It also reviews the available experience with the most common anticancer regimens as well as each chemotherapeutic agent. Chemotherapy during the first trimester may increase the risk of spontaneous abortions, fetal death, and major congenital malformations. The teratogenic effects depend on the dosage, time of administration, and cumulative exposure to the chemotherapeutic agent. The choice of treatment for the pregnant patient with cancer has become even more complicated due to the increasing use of targeted anticancer therapies. J. I. Durodola reported that an infant that had received cyclophosphmide became neutropenic from breastfeeding. The chapter summarizes the important reports concerning different cytotoxic agents, and presents each medication according to its pharmacological group and time of publication. The chapter also provides a brief description of the study and the pregnancy outcome.