PURPOSE: To evaluate the clinical usefulness of defecogrophy in diagnosing the etiology and pathophysiology of constipation. A retrospective study of 56 constipated patients who had no abnormalities in colonoscopy, barium enema and rectal exam were done. METHODS: Fifty-six patients (12 men, 44 women) with constipation underwent defecography and 37 of the patients underwent colonic transit studies. Fluoroscopically guided defecography was performed with barium paste introduced into the rectum. RESULTS: Normal defecography finding was observed in thirteen of the 56 patients. Rectocele, spastic levator syndrome (nonrelaxing puborectalis syndrome), sigmoidocele, rectal prolapse, rectal intussusception were observed in 67% (38/56), 30% (20/56), 7% (4/56), 5% (3/56) and 2% (1/56) of the patients, respectively. More than one pathological finding was found in 23 (53%) patients. Of the 38 rectoceles, 17 cases were found to be associated with spastic levator syndrome. In solitary rectocele, the anorectal angles at rest, during straining were 92.65 9.08o, 108.09 14.35o, while 99.85 11.85o, 95.90 17.84o, in spastic levator syndrome. In 36 difficult bowel movements, 66% (24/36), 30% (11/36), 3% (1/36) were found to have rectocele, spastic levator syndrome, and sigmoidocele, respectively. Normal colonic transit time was observed in twenty six of the 37 patients. Abnormal findings included colonic inertia in 3 (8%) patients, hindgut dysfunction in 4 (11%) patients, and, outlet obstruction in 4 (11%) patients. Of the normal colonic transit time in 26, rectocele in sixteen, rectal prolapse in 1, spastic levator in 2 were observed. Rectoceles were observed in 2 out of 3 colonic inertia, in all 4 hindgut dysfunction, in 1 out of 4 outlet obstruction. CONCLUSIONS: Our findings suggest that constipation is often a disorder of defecation rather than a impairment of colonic motility. Defecography should be considered first of all in evaluating the pathophysiology of constipation, especially for whom complaining of difficult bowel.