Ninety-one patients with idiopathic constipation had segmental colonic transit studied with radiopaque markers using a new simplified technique to determine frequency and type of colonic transit time (CTT) abnormalities and to determine the utility of this test in planning therapy. Colonic transit studies defined four groups: normal CTT (N = 49), right colonic stasis (N = 16), outlet obstruction (N = 12), and isolated left colonic stasis (N = 14). Right colonic stasis and outlet obstruction were associated with frequent use of digital pressure to assist defecation. Right colonic stasis was characterized by a low stool frequency (less than 3 per week) in 93% of cases and failure to respond to bran therapy. Outlet obstruction also showed a poor response to bran therapy but weekly stool frequency was higher than 3 in 46% of cases. Normal colonic transit time and isolated left colonic stasis were characterized by a normal stool frequency (5.8 +/- 0.05 and 4.2 +/- 0.1, respectively) and clinical help with the use of bran treatment (72 and 64%, respectively). Our study suggested that patients who complain of idiopathic constipation represent a heterogenous group of disorders. Segmental CTT determination is a simple, useful, and noninvasive test of patients with constipation.