The aim of this study was to identify myenteric ganglion cells (MGC) and interstitial cells of Cajal (ICC) from the total colectomy specimen in patients with chronic idiopathic constipation. Fourteen patients who had severe, intractable, long-standing (mean: 14 years) constipation underwent subtotal colectomy and ileorectal anastomosis. All resected specimens were investigated with hematoxylin and eosin (H&E) and immunohistochemical staining with anti-neurofilament monoclonal antibody NF(2)F(11) for MGC, and c-kit antibody for ICC. The numbers of MGC and ICC were counted for ascending (AC), descending (DC), and sigmoid colon (SC). We compared these data with those from ten control specimens. The number of MGC was significantly smaller in AC and DC of the constipated group than in the control group. Interestingly, SC contained a similar number of MGC. The two staining methods were equally effective for identifying MGC. The total ICC number in the constipated group was markedly lower in every segment. Most anatomical layers of the colon, including the submucosal border, circular muscle, and longitudinal muscle, revealed a similar tendency. However, in the myenteric plexus area there was no significant difference between the two groups. A quantitative decrease in MGC and ICC appears to be implicated in chronic idiopathic constipation.