Pancuronium, gallamine, and succinylcholine produced more profound neuromuscular blockade in 36 patients anesthetized with 1.25 MAC Forane than in 36 patients anesthetized with 1.25 MAC halothane. The median effective dose of pancuronium necessary to produce 50 per cent depression of twitch height (ED20) was 0.27 mg/m2during Forane and 0.49 mg/m2during halothane anesthesia, giving a halothane/Forane potency ratio of 1.8. The ED20of gallamine was 9.4 mg/m2during Forane anesthesia and 22.5 mg/m2during halothane anesthesia, for a potency ratio of 2.4. The ED20of succinylcholine was 3.4 mg/m2during Forane anesthesia and 5.1 mg/m2during halothane anesthesia, for a potency ratio of 1.5.