Antirheumatic drugs in pregnancy and lactation are increasingly a common clinical dilemma. With the shift towards early, aggressive control of autoimmune diseases and with the advent of newer therapeutic agents, there is a need to understand the effects of these medicines in pregnancy and lactation, on fertility in both men and women, and on the process of spermatogenesis, in order to understand the risk of teratogenesis. Although there are some limited data available for the use of antirheumatic drugs in pregnancy and lactation, much of our knowledge is derived from animal models and from limited clinical experience in human pregnancy. The balance of therapeutic benefits and risks of harm to mother and fetus should always be carefully considered: it may vary between individuals and should be assessed on a case by case basis. Because of these issues, pregnancy should always be discussed and planned in advance, in part to reduce disease activity prior to conception but also to minimize risk to the fetus. In this chapter we use the available evidence to discuss medicines which are commonly used in the treatment of rheumatological autoimmune diseases, and cover disease-modifying antirheumatic drugs (DMARDS) and biological agents.