Dramatic media reports of recent outbreaks of illness caused by Escherichia coli O157:H7 have drawn national attention to this emerging pathogen. In 1993, a widely publicized outbreak of over 500 culture-confirmed cases was traced to fast-food hamburgers in Washington, Idaho, Nevada and California. Closer to home, the first (and still the largest) reported waterborne outbreak of this disease occurred in Cabool, Missouri in 1989. That outbreak affected 243 people, of whom 32 were hospitalized, 2 had hemolytic uremic syndrome, and 4 died. E. coli O157:H7 was added to the list of reportable diseases in Missouri in mid-1992, but its importance is still not widely recognized. This article reviews the results of state and national surveillance for the disease, and suggests methods for improving diagnosis and reporting.