In a prospective study carried out in New Halfa Teaching Hospital, in eastern Sudan, between June 2001 and April 2003, 25 pregnant Sudanese women with schistosomiasis mansoni were each treated with a single oral dose of praziquantel (PZQ), at 40 mg/kg. The drug was given to six (24%), 12 (48%) and seven (28%) of the women during the first, second and third trimesters of their pregnancies, respectively. The patients were followed-up until delivery and their babies were followed-up until they were 1 year old. Although one patient, who received PZQ after 10 weeks of gestation, aborted (3 weeks post-treatment), this frequency of abortion is similar to that seen in the local community. None of the treated women died, and there were no stillbirths or congenital abnormalities in the newborn babies. Although this is a small trial, it appears that PZQ is a safe drug to use against schistosomiasis mansoni, even during the first trimester of pregnancy.