Diarrheal disease is still one of the major diseases in public health problems in Indonesia because of its high incidence and mortality. Almost all cases of acute diarrhea are caused by bacterial infection, the most frequent of which is diarrhea, an infection of the bacterium Escherichia coli (E. coli). These bacteria enter the human body through the hands or through tools such as bottles, pacifiers, thermometers and eating utensils contaminated by the feces of patients or carriers. The purpose of this study is to determine the correlation between the conduct of mothers as users of milk bottles for their infants in Sub-District Kayuringin South Bekasi Jaya, Bekasi District in 2008. A total of 160 persons made up the sample of mothers who participated in this study, which centered on the ways in which the bottles used for the infants were cleaned and the milk prepared. The results of the study showed that there was no correlation between the conduct of the mothers and the presence of E. coli. The result of the study implies that there are other factors that may be leading to the occurrence of diarrhea, such as environmental and individual health factors, specifically those related to hygiene, socio-cultural factors, nutritional factors, and social factors.