It was the aim of this study to assess the effects of cisapride on gastrointestinal transit of solids in healthy humans. Twelve men received cisapride 10 mg or placebo orally four times a day in random, double-blind, crossover fashion. Transit measurements were performed with a new gamma camera technique. Cisapride reduced mean gastric emptying time of 99mTc-labeled cellulose fiber [0.77 (0.69-1.12) hr [median (range)] vs 0.98 (0.63-1.95) hr; P less than 0.05] and 1- to 2-mm 111In-labeled plastic particles [1.08 (0.50-1.42) hr vs 1.69 (0.59-3.03) hr; P less than 0.01]. Cisapride also decreased mean small intestinal transit time of cellulose fiber [2.11 (0.80-5.08) hr vs 2.82 (0.78-7.12) hr; P less than 0.05] and plastic particles [2.06 (1.13-5.13) hr vs 2.64 (1.18-7.04) hr; P less than 0.05]. However, cisapride increased mean large intestinal transit time of plastic particles [31 (13-75) hr vs 23 (12-36) hr; P less than 0.05]. In conclusion, oral cisapride 10 mg four times a day accelerates gastric emptying and small intestinal transit whereas this dose of cisapride seems to delay large intestinal transit of solids in healthy humans.