3 cases of ulnar nerve paralysis following general anesthesia are reported. In all of 3 cases, there were no anatomical abnormalities and any neurologic disease, and no traumatic history before operation. And there were no specific findings in laboratory and radiologic examination. It is suggested in the absence of any causative factors other than malposition. In two cases, the paralysis disappeared without specific therapy in 4 to 5 weeks, but in one case, the paralysis was more severe and the improvement was not remarkable with physiotherapy for 3 months.