We examined the effects of unilateral nephrectomy (UN) and administration of indomethacin in 15 healthy humans. Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), urine flow, sodium and potassium excretions, urinary excretion rate of prostaglandin E2 (PGE2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) in the remaining kidney were all significantly (p < 0.01) increased 10 days after UN. Indomethacin administered at 75 mg/day for 3 days abolished the increase in GFR, ERPF and sodium excretion with reduced urinary excretion rate of PGE2 and 6-keto PGF1 alpha but not the increase in urine flow and potassium excretion. These findings suggest that renal prostaglandins may play a role in renal functional adaptation following UN.