Progressive systemic sclerosis (PSS) may involve any portion of the gastrointestinal tract, including the colon. Constipation is common in patients with PSS. Cisapride, a benzamide derivative, is a potentially useful agent in the treatment of chronic idiopathic constipation. The effect of cisapride on colonic transit was evaluated in 16 PSS patients by a radionuclide colonic transit method. Each patient received cisapride orally three times a day for a week. The results showed acceleration in colonic transit in response to cisapride. We conclude that cisapride is effective in the treatment of constipation in patients with PSS.