A young desert bighorn ram (Ovis canadensis) approximately 8 months old was found ill in its natural habitat. Inoculation of a suspension of its lung tissue into domestic sheep resulted in lesions typical of bluetongue disease. Serological studies confirmed the diagnosis. The possibility is presented that this disease may have been partially responsible for the disappearance of the desert bighorn from the Trans-Pecos area of Texas. Bluetongue is a viral disease of sheep primarily, although cattle and goats may be affected (Howell 1963). It has been hypothesized that wild ruminants are reservoirs of infection. Experimental transmission to the blesbuck (Damaliscus albifrons) (Neitz 1933), an African antelope, has been achieved. No clinical signs were reported. This disease is widely distributed in Africa and the Middle East but was not reported in North America until fairly recently. An entity, first called "soremuzzle" and later identified as bluetongue, was reported in Texas by Hardy and Price (1952), and it is believed that the disease was present in Texas several years earlier than this report (Hardy 1966, Personal communication). Dr. D. H. Bennett described the lesions and epidemiology of "soremuzzle" in Texas as early as 1923 in a communication with Dr. H. Schmidt. Transmission of the virus isolated in Texas was accomplished experimentally in sheep by the use of insects of the genus Culicoides (Price and Hardy 1954). The incubation time in sheep varied from 1 to 2 weeks and the severity of the disease was variable and unpredictable. The clinical signs observed in domestic sheep usually include an increase in temperature, hyperemia of the mucous membranes, and swelling of the face and lips (Howell 1963). Buccal erosions may occur and coronitis is often observed in animals with light colored hooves. A clear mucopurulent nasal exudate usually is present, and terminal pneumonia commonly occurs in fatal cases. The disease must be reproduced in susceptible sheep to establish a positive diagnosis. The occurrence of this disease in wild ruminants such as deer, bighorn, and pronghorn antelope has not been reported, although it has been reported in domestic sheep (Howell 1963) throughout the southwestern United States.