Virus neutralising antibodies to malignant catarrhal fever virus were demonstrated in the sera of 50 oryx (Oryx beisa callotis). The mean antibody titre in 42 adult oryx was 10.^1.23 Two calves which were 2 weeks old had a mean titre of 10^1.54 but the level of circulating antibody had started to decline in 2 months old calves. The antibody titres continued to decline only to rise steeply in 9 months old calves. Despite the high prevalence of antibodies in oryx no virus was isolated from blood or nasal secretions inoculated into calf thyroid cell cultures or rabbits.