Chronic constipation is a common clinical condition that frequently does not respond to routine therapeutic measures. We hypothesized that colchicine would be effective in this condition because we reported that it stimulates intestinal motility in rats and commonly causes diarrhea in patients taking the drug for either gouty arthritis or Familial Mediterranean fever. We prospectively studied seven patients with chronic constipation who were refractory to medical therapy and treated them with oral colchicine 0.6 mg per os three times a day for eight weeks in an open-label pilot study. During the study, the mean number of spontaneous bowel movements significantly increased (P < 0.05) from 1.7 +/- 0.5 noted during routine therapy of constipation with laxatives and enemas to 6.4 +/- 0.7 per week; mean colonic transit time significantly (P < 0.05) decreased from 58.1 +/- 2.5 to 47.1 +/- 5.0 hr; and symptoms of abdominal pain, nausea, and bloating significantly (P < 0.05) improved during therapy with colchicine. Oral colchicine (0.6 mg three times a day) therapy appears to be an a promising treatment for chronic constipation and a placebo-controlled trial is indicated to confirm these findings.