From instances of diarrhea of the newborn in four separate hospital outbreaks a filtrable agent was isolated which regularly produced diarrhea in calves. This agent appeared to have the characteristics of a filtrable virus.
The four strains of virus isolated in the outbreaks studied appeared to be identical or very closely related.
The virus was not found present in the stools of any of eight normal newborn infants or five normal calves.
Evidence is presented that the virus may be one of the causes of epidemic diarrhea of the newborn.