BACKGROUND: Intermittent preventive treatment with sulphadoxine-pyrimethamine has been adopted as part of the malaria control strategy in pregnancy in Nigeria. Some studies have however failed to reproduce all the benefits initially credited to this regimen. This study seeks to appraise the effectiveness of this regimen in the prevention of placental malaria and certain pregnancy outcome among parturients in Calabar. METHODS: Pregnant women were assigned to receive two or three doses of sulphadoxine-pyrimethamine under direct observation at the antenatal clinic. Pregnant women who did not receive any dose of this drug in pregnancy for various reasons constituted the control group. At delivery, gestational age, packed cell volume, birth weight, cord and placental parasitaemia were measured and analysed with SPSS.