Experimentally induced toxoplasmosis in pregnant ewes was treated with a combination of sulphamezathine and pyrimethamine. Fifteen untreated ewes gave birth to 14 live and six dead lambs whereas all the 15 lambs born to the 12 treated ewes were viable. The placental lesions were less severe, the gestation period was longer and the precolostral antibody titres to Toxoplasma gondii were lower, all significantly, for the lambs born to the treated ewes.