INTRODUCTION: Infection with Toxoplasma gondii is asymptomatic or mild in immunocompetent people and leads to lifelong immunity, but it can have serious consequences in pregnancy. About five per 1000 non-immune pregnant women may acquire toxoplasma infection, with a 10% to 100% risk of transmission to the baby. Risks of transmission to the baby are higher later in pregnancy, but risks of infection causing harm to the baby are greater earlier in pregnancy. METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical questions: What are the effects on mother and baby of treating toxoplasmosis during pregnancy to reduce risk of vertical transmission and treat fetal infection? What are the effects of treating toxoplasmosis in neonates infected with toxoplasmosis prenatally? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). RESULTS: We found six systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. CONCLUSIONS: In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiparasitic drugs in pregnancy, and antiparasitic drugs in neonates. QUESTIONS What are the effects on mother and baby of treating toxoplasmosis during pregnancy to reduce risk of vertical transmission and treat fetal infection?.