Orthoreoviruses have been associated with disease in reptiles, but have not previously been isolated from snakes with inclusion body disease (IBD). An orthoreovirus was isolated from a Boa constrictor diagnosed with IBD and then used to conduct a transmission study to determine the clinical importance of this virus. For the transmission study, 10 juvenile boas were experimentally infected with the isolated orthoreovirus and compared to 5 sham-infected control animals. Orthoreovirus was reisolated for a period of 18 wk after infection and weight gain was reduced in infected snakes. Histological examination showed a mild hepatitis in three of four virologically positive snakes up to 12 wk after infection. Results indicated that the orthoreovirus was moderately pathogenic, but, no evidence was found to indicate that it was the causal agent of IBD. In the light of the discovery of Arenaviruses in some snakes with IBD, it was proposed that orthoreoviruses may play a role in synergistic infection.