Five cell culture isolates from transmissible gastroenteritis (TGE) of swine have been studied. There is a cytopathogenic virus common to all of these isolates. Some of the characteristics of this virus, such as its size, approximately 100 mmicro, its relative sensitivity to ether, lability at pH 2, pH 3, and pH 10, and its heat lability suggest that it may be a member of the myxovirus class. Concurrent research in this laboratory indicates that this cytopathogenic virus is not the only virus involved in the etiology of TGE, but it appears to be associated with many of the outbreaks of TGE which have been studied by this laboratory.