In order to evaluate the clinical significance of urinary human epidermal growth factor (hEGF) in patients with acute renal failure (ARF), urinary hEGF levels were determined by radioimmunoassay, and were corrected for creatinine (creat.) concentrations in 16 patients with ARF and 12 healthy controls. The urinary hEGF levels significantly decreased in patients with ARF in acute phase compared with normal control subjects (0.98 +/- 0.20 vs 13.74 +/- 1.18 ng/mg creat. p less than 0.01), and it subsequently increased during recovery phase (6.10 +/- 0.73 ng/mg creat. p less than 0.01 vs acute phase). A significant correlation between the urinary hEGF levels and creatinine clearance (r = 0.712, p less than 0.001) and an inverse correlation between urinary hEGF levels and fractional excretion of sodium (r = -0.406, p less than 0.05) was demonstrated. The remarkable decrease of urinary hEGF excretion preceded the increase of urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase levels. Our data suggests that urinary hEGF originates from renal tissues in humans and measurement of urinary hEGF is useful for diagnosing renal damage and recovery of renal tissues from severe tubular injury.