Strength of contraction of small muscles of the hand, foot, or face elicited by electrical stimulation of the motor nerve was estimated during administration of a muscle relaxant in 65 anesthetized patients. The purpose was to evaluate whether relative strength of muscle contraction provided a useful indication of surgical requirements. Maintaining a flicker of evoked muscular contraction, shown to represent 5% to 10% of normal neuromuscular transmission, provided profound abdominal muscle relaxation and adequate operating conditions in 63 of 65 patients. Normal neuromuscular transmission had returned in 29 patients at termination of anesthesia. Transmission was restored in an additional 31 patients by giving neostigmine. In five patients relaxant action was not or could not be reversed by neostigmine. In the latter group respiration was assisted until tests of neuromuscular function showed normal function.