During the first two weeks of March 2004, 80 carrion crows (Corvus corone) were found dead in a park in Brussels (Belgium). At necropsy, splenomegaly, hemorrhagic enteritis with duodenum lesions and cerebral or meningeal hemorrhages were observed reminiscent of West Nile virus infection. By real-time (RT)-PCR (reverse transcription polymerase chain reaction), no amplification of the West Nile disease virus-specific 3’UTR RNA sequence was observed, while viral isolation from brain homogenate was also negative. Toxicological examination revealed no toxins. Transmission electron microscopy demonstrated intracytoplasmic, reovirus-like particles in ultra-thin sections of the spleen and duodenum. Proliferation of these virions in cultured chicken embryonic hepatocytes was evidenced by their cytopathogenic effect and their presence in infected cells and their supernatant.