A new diarrhoeic syndrome was examined clinically in 19 one to two-week old Charolais calves. It differs from other digestive disorders in calves of this age in the discrete diarrhoeic signs, the absence of dehydration and the presence of signs of ataxia. The microbiological study carried out for three consecutive years in 58 sick calves and nine healthy control calves demonstrated the special role of E coli possessing virulence markers from septicaemic strains (CS31A, Col V). The clinical signs could be the result of bacteraemia with subacute E coli endotoxaemia.