From April 1974, we have performed modified neurcleptanesthesia with diazepam-pentazocine N2O in 60 cases. These patients were given diazepam, 0.3 mg/kg, and pentazocine, 1 0 mg/kg, intravenously. Endotracheal intubation was performed in all cases after a sleep dose of thiopental or N2O by mask, with an adequate dose of succinylcholine. Anesthesia was maintained with N2O-O2, suplemented with muscle relaxants. During the operation, we gave an additional dose of diazepam or pentazocine, if needed. The results were as follows: Respiratory depression was observed after the administration of diazepam and pentazocine, but this depression disappeared in the early postoperative recovery period. 2. Recovery from anesthesia was rapid and smocth. Almost all patients awakened within 5 minutes after discontinuance of N2O admir.istration. 3. Analgesia and sedation extended well into the postoperative period, minimizing the need for narcotics. 4 Postoperative nausea and vomiting appeared in only 7% of cases. 5 Circulagory stability was marked during and after operation, being particulary valuable in the elderly and poor risk patients.