Nubian goats owned by 18 families who ran a co-operative farm in Nanaimo, British Columbia, produced milk that was contaminated with E. coli O157:H7. The outbreak first affected the children of a family new to the co-operative. Later the children of a family visiting the co-operative farm became ill. Milk samples were analyzed and found to contain the same strain of E. coli O157:H7 that was isolated from the three laboratory confirmed cases. Pasteurization of milk was required by law in British Columbia, however this milk was not pasteurized prior to consumption.