The kinetics of erythromycin (E.) was studied in 16 patients with different degrees of impairment of renal function after a single intravenous dose. Renal clearance of E. was found to be significantly correlated to the creatinine clearance. Total recovery in urine did not exceed 7.5%. As expected from the small fraction excreted via the kidneys, the elimination half-life and the total clearance of E. did not depend on renal function. We conclude that impairment of renal function does not justify a dose adjustment of E. Hearing acuity should, however, be monitored during treatment since transient deafness predominantly in patients with renal failure has been reported by various authors.