Although a quarter of children who survive diarrhea-associated hemolytic uremic syndrome develop long-term renal sequelae, the prognosis of acute, self-limited Escherichia coli O157:H7 gastroenteritis has never been previously studied. Four years after a drinking water outbreak of E. coli O157:H7, we examined the risk of high blood pressure (>95th percentile expected for age, sex, and height), reduced kidney function, and microalbuminuria among previously healthy children and adolescents. Of the 951 participants, 313 were asymptomatic during the outbreak, 305 had moderate symptoms of acute gastroenteritis, and 333 had severe symptoms that necessitated medical attention. An additional 23 children who developed hemolytic uremic syndrome during the outbreak were excluded from this analysis. There were no differences in mean systolic blood pressure between those who had no, moderate, or severe symptoms of acute gastroenteritis during the outbreak (109, 110, and 107 mm Hg). Similarly, there were no group differences in diastolic blood pressure, estimated glomerular filtration rate, or random urine albumin to creatinine ratio (P ranged from 0.14 to 0.52), or in the adjusted relative risk of high blood pressure, a glomerular filtration rate <80 ml/min per 1.73 m(2), or microalbuminuria (P ranged from 0.23 to 0.89). Patients who presented to medical attention with gastroenteritis during this E. coli O157:H7 outbreak had an absence of renal sequelae 4 years later. With no existing data to support screening after self-limited E. coli O157:H7 gastroenteritis, we recommend that only those children who develop recognized features of hemolytic uremic syndrome be followed for long-term renal health.