We have determined glomerular filtration rate (GFR), renal plasma flow (RPF), urinary excretion of albumin and beta 2-microglobulin, urinary osmolality and total renal area in 22 female patients with renal scarring and a history of febrile urinary tract infections (UTI) and in nine healthy age-matched controls with normal i.v. urography. The aim of the study was to compare different methods of determining glomerular function in patients with renal scarring due to previous pyelonephritis and to determine the urinary excretion of beta 2-microglobulin in these patients. All individuals were investigated in hydropenia. The patients with renal scarring had significantly lower GFR, smaller kidneys and lower urinary osmolality than the controls. A significant positive correlation between GFR and total renal area (r = 0.70, p less than 0.001) and between GFR and urinary albumin excretion (r = -0.69, p less than 0.001) was demonstrated. This indicates that determinations of total renal area from an i.v. urography and the urinary albumin excretion can be used for estimating GFR. Increased urinary excretion of beta 2-microglobulin does not occur in patients with renal scarring until the glomerular function is severely deteriorated.