Two cases of severe hearing loss due to intravenous administration of erythromycin lactobionate are described. Documented, bilateral sensorineuronal hearing loss developed in both patients and gradually improved when the dose of erythromycin was decreased. Neither patient had severe renal dysfunction (documented clearances of 25 to 30 mL/min), but both had hepatic dysfunction with elevated bilirubin levels. Additionally, both were receiving other ototoxic drugs concurrently. Both patients also had an acute psychotic reaction that was temporally related to the ototoxicity and high-dose erythromycin therapy.