Plasma cholecystokinin levels were measured in children with recurrent abdominal pain to investigate the relationship of plasma cholecystokinin levels with colonic transit patterns and clinical symptoms. Subjects consisted of 120 children (mean age 9.6 ± 2.6 years) for whom colonic transit study had also been done. Plasma cholecystokinin levels were 79.2 ± 58.7 pg/mL in children with colonic inertia, 70.7 ± 47.0 pg/mL in hindgut dysfunction, 57.4 ± 53.1 pg/mL in pelvic outlet obstruction, and 67.6 ± 47.9 pg/mL in normal colonic transit. These data showed that there was a tendency of increasing plasma cholecystokinin levels in children with proximal colon transit delay, although there was no significant difference among four groups. Plasma cholecystokinin levels in children of 10 years of age and under (54.5 ± 40.4 pg/mL) were significantly lower (p = 0.01) than in children over 10 years (79.1 ± 59.8 pg/mL). Plasma cholecystokinin levels based on colonic transit patterns, however, were not significantly different between the two age groups. There was no significant difference in plasma cholecystokinin levels between groups based on defecation frequency per week, presence of defecation pain, symptoms of milk intolerance, or the presence of emotional stress. These results suggested that there was a tendency of increasing plasma cholecystokinin levels in the younger age group and in children with delay in proximal colonic transit, but further study is required in relation to plasma cholecystokinin levels based on colonic transit patterns in a large number of patients.