On the basis of colonic transit study using radiopaque markers, patients with constipation may be divided into three different groups. In the first, there is delay in the colon (colonic inertia). In the second, feces pass normally along the colon but are stored too long in the rectum (outlet obstruction). In the third, transit time of the radiopaque marker is normal. To distinguish between different types of constipation is the first step in the evaluation of patients with chronic constipation. There is the variability of colonic transit related to the intake of dietary fibers. As quite difference between Korean food and Western food, colonic transit in Korean may be different to that of in Western people. The aim of this study was to evaluate the colonic transit in healthy Korean. Segmental colonic transit with commercially available radiopaque markers was stuided in 60 healthy volunteers. Subjects ingested one capsule (20 radiopaque 0-rings) at 9:00 AM on each of 3 consecutive days while they are fully ambulatory. A plain radiograph of the abdomen was obtained on the 4th or 7th day. Total colonic transit was 10.57 (+12.80) hr (meanSD); segmental transit was 3.87 (+7.23) hr for the right colon, 3.31 (+- 5.01) hr for the left colon, 3.27 (+- 5.66) hr for the rectosigmoid. Sex did not influence transit significantly. This study shows that Koreans have markedly faster transit than Western and technique is simple and convenient for clinical usage.