Although it has been accepted that metoclopramide provides the effects of antiemetics, enhance- ment of intestinal motility and acts as antagonist on dopamine receptor, there is still controversy over inhibitory action of plasma cholinesterase. We examined the effect of preoperative intravenous administration of metoclopramide 10mg (group 2,4) on the duration of neuromuscular block induced by an intubating dose (1 mg/kg) of succinylcholine. Forty female adult patients were devided into four groups, scheduled for cesarean section (group 3,4) or other elective operations (group 1,2). The 1 H2single twitch height of the adductor pollicis muacle was recorded on paper to 1 H2single twitch stimulus by a nerve stimulator (Accelograph). The patients in group 2 and 4 received metoclopramide 10 mg i.v followed by succinylcholine 1mg/kg, and the patients in group 1 and 3 received succinylcholine 1mg/kg alone. The time from disappearance of 1 H, single twitch height to reappearance of that did not significantly differ between group l and 3. However, there was significant prolongation of the time from disappearance of 1H2single twitch height to reappearance of that in patients who received metoclopramide followed by succinylcholine in group 2 and 4. Also, we examined the effect of preoperative intravenous administration of metoclopramide 10mg on the duration of neuromuscular block by 0.5mg/kg of succinylcholine in twenty female patients for elective operations (group 5,6). There was no significant prolongation of the time from disappearance of 1 H, single twitch height to reappearance of that.