Background/Aims: The clinical evaluation of rectal sensation has traditionally relied on the use of balloon distension in the rectum but balloon distension test has been limited because it was seen variably. This study was performed to evaluate usefulness of electrophysiologic test in patients with chronic constipation. Methods: Pudendal nerve terminal motor latency(PNTML), anal and rectal rnucosal electrosensory test, balloon distension test and defecogram were performed in 19 patients with chronic constipation and 1 1 normal controls. Results: There was no significant difference between patients with chronic constipation and normal controls in balloon distension test but balloon distension in the rectum revealed an elevated tendency of sensory threshold in constipated patients. The mean value of right and left PNTML did not differ between tendency in patients with chronic constipation and controls(2.65+0.94 vs. 2.20+0.33 msec, patients vs. controls, p=0.2448). Rectal rnucosal electrosensory threshold revealed an elevated tendency in patient with chronic constipation(50.8>23.6 vs. 40.9+10.1 mamps, patients vs. controls, p=0.0838) but there was no significant difference between patients with chronic constipation and controls in anal threshold. PNTML revealed an elevated tendency in patients with prominent puborectalis on evacuation(2.71 +0.72 vs. 2.03+0.40 msec, p=0.0776), but anal and rectal mucosal sensory threshold did not differ depending on puborectalis dyskinesia. Conclusions: Because rectal mucosal electrosensory threshold revealed an elevated tendency in patient with chronic constipation and PNTML revealed an elevated tendency in constipated patients with prominent puborectalis on evacuation, it is thought that the changes of rectal mucosal sensory threshold and PNTML in patients rnay be related with clinical symptoms and etiology.