We measured glomerular and tubular function in 10 children, aged 7 to 19 years, 7 to 12 years after apparent recovery from their episodes of acute renal failure. Although glomerular filtration rate was normal in all, filtration fraction (inulin clearance/PAH clearance) was elevated in six of eight patients. Segmental tubular sodium transport was assessed using clearance techniques during hypotonic saline diuresis; both proximal and distal sodium reabsorption were normal when compared with age-appropriate normal standards. Tubular reabsorption of phosphate, glucose and amino acids were also normal, as were urinary concentrating and diluting capacity and distal tubular hydrogen ion secretion. We conclude that, despite normal glomerular filtration rate, glomerular function is abnormal in a significant number of children who have apparently recovered completely from ARF, probably due to destruction of a proportion of the total nephron population, predominantly those located in the superficial layers of the cortex.