A series of 201 private patients bronchoscoped for diagnostic or therapeutic reasons was administered the new compound diazepam (Valium) as adjunctive premedication aimed at reducing anxiety. Dosage was intravenous, at a level of 5 to 7.5 mg. for most patients. In appraising drug effects, the parameters of intact cough reflex, relaxation, cooperation and amnesia for the procedure were of paramount importance. Five showed poor response, seven others fair, and 189 (93.5 per cent) were rated good or excellent by all criteria. The authors consider diazepam a promising drug for use in endoscopy. There was no serious complication and no evidence of respiratory depression or hypotension. This study was originally undertaken because of the muscle relaxing properties of diazepam discovered by other investigators. A certain amount of muscle relaxation was in fact obtained during endoscopy, facilitating the procedure. However, a more interesting effect of this drug was its amnesic action. In interrogating the patients several hours after endoscopy, the great majority remembered the administration of the topical anesthetic, but little or nothing of the following procedure. Thus intravenous diazepam used in conjunction with preoperative sedation and topical anesthesia has removed the unpleasant effects to the patient of bronchoscopy and esophagoscopy, without producing any serious complication. It is our opinion that diazepam will prove to be valuable and helpful in endoscopy in the future.