Introduction: Among the colorectal physiologic tests, the assessment of colonic Transit time (C.T.T) is a simple and useful one. The aim of this study was to evaluate the occurance of C.T.T abnormalities in chronic idiopathic constipation, correlate C.T.T patterns with symptoms, and to evaluate the effect of age, gender, psychological factors, IBS and daily physical activity on total and segmental colon Transit.Methods: A total of 31 patients with chronic idiopathic constipation completed questionnaires; and underwent C.T.T by radio-opaque markers. Correlation were performed between the above variables and C.T.T. Results: Out of 31 patients (24 women, 7men; mean age 38.7yr), 14 patients (45.2%) had abnormal C.T.T Colon Transit. The results could be categorized into four groups: normal C.T.T (n=17), right colonic stasis (n=6), isolated left colonic stasis (n=7) and rectosigmoid stasis (n=1). There was a significant correlation between the age above 50 yr and abnormal C.T.T (p<0.05). There was also a significant correlation between the hard stool and abnormal C.T.T (p<0.05). There were no correlation between gender, daily physical activity, psychological status, IBS and C.T.T. Discussion: Our study suggested that chronic idiopathic constipation represent a heterogeneous group of disorders. Defining constipation on the basis of patients reported stool frequency is not reliable and ,hard stool is the best reliable symptom. C.T.T study is a simple, useful and noninvasive test for patients with constipation.