A Kabete 'O' strain of rinderpest virus enhanced in virulence was inoculated subcutaneously into four cows which were between six and eight months pregnant. All the cows developed clinical signs of rinderpest from the third day after inoculation and shed high titres of virus in their ocular and vaginal secretions during the course of the clinical disease. Three of the cows died of rinderpest on the third day after the onset of fever but no virus was isolated from their fetuses which were examined post mortem. The fourth cow showed complete clinical and virological recovery by the eighth day after the onset of fever and aborted an eight-and-a-half-month-old fetus on the 12th day after it recovered. Rinderpest virus was demonstrated in a wide range of the aborted fetal tissues. Virus was also detected in the maternal vaginal discharges up to 24 hours after abortion. The only gross pathological change observed was a severe necrotising placentitis.