Malaria is a common infection worldwide. Increased travel by pregnant women makes it likely that physicians in the United States will see cases of malaria in this population. We observed four cases of malaria during pregnancy over an 8-month period at a general hospital in the United States. These cases illustrate the association between pregnancy and severe malaria in the mother and congenital infection in the newborn. We also noted delays in diagnosis because malaria was mistaken for other common illnesses. Therapy was complicated by concerns about the safety of antimalarial agents for the fetus and newborn as well as drug resistance. While chloroquine is safe for use in pregnancy, drug resistance is now common, especially when the etiologic organism is Plasmodium falciparum. There are concerns about the safety of administering other antimalarial agents during pregnancy (e.g., mefloquine). Concerns about the safety and availability of these agents limit options for prophylaxis. © 1992 Oxford University Press.