Prognostic significance of proteinuria one year after onset of diarrhea-associated hemolytic-uremic syndrome. We examined the prognostic value of changes in the amount of proteinuria, measured as protein/creatinine ratios in early-morning urine samples, in 40 children who had had diarrhea-associated hemolytic-uremic syndrome. One year after diagnosis, 87% of those who seemed to have fully recovered had normal urinary protein/creatinine ratios, compared with none of those with poor outcomes (p less than 0.001). None of those with poor outcomes achieved normal protein/creatinine ratios during follow-up to a maximum of 5 1/2 years, but 93% of those who made a full clinical recovery no longer had proteinuria. Measurement of the protein/creatinine ratio in an early-morning sample of urine is a simple, cost-effective, and noninvasive means of monitoring the progress of patients with diarrhea-associated hemolytic-uremic syndrome, provided that a technique sensitive at low protein concentrations is employed. 