Clinical data from 246 patients presenting with a nephrotic syndrome and biopsy-proven glomerular disorder were analyzed, using statistical survival techniques, to determine which of several variables (sex, age, plasma creatinine, diastolic blood pressure and 24-hour urinary protein loss) were associated with subsequent end-stage renal failure. The best prediction of outcome could be made at one year (N = 121); then plasma creatinine (P less than 0.001) and heavy proteinuria (P = 0.049) were the best determinants. For a given plasma creatinine level, heavy urinary protein was associated with a worse outcome. The incidence of end-stage renal failure was greatest three to four years from the date edema first developed. Plasma creatinine and urinary protein values, collected four-monthly throughout the study period, were analyzed as time-dependent covariates. A relationship was found between the prevailing risk of renal failure and earlier heavy proteinuria (P less than 0.001). Spontaneous complete remission of proteinuria was associated with a highly favorable outcome (P = 0.001) and normal, or impaired but stable, renal function.