A study of stool Escherichia coli in 60 children with gastroenteritis and 18 control children was carried out in Auckland, New Zealand in 1977. Toxigenic strains, heat labile and heat stable, predominated in the stools of only three children, all of whom had concomitant rotavirus. Classical enteropathogenic E. coli (EPEC) were found in patients and controls. Only one patient had many EPEC in the stool (086.H2), they were variably toxigenic and rotavirus was also present. No toxigenic serotype was isolated. Two potential pathogens were sometimes found. Overall there was no evidence for a substantial causative role for disease producing E. coli in these children.