After Roux-en-Y gastrojejunostomy patients frequently complain of upper abdominal pain, fullness, nausea, and vomiting. This Roux-en-Y syndrome is caused by slow gastric emptying, Roux-limb stasis, or both. Treatment of this syndrome is cumbersome. We evaluated the effect of cisapride on complaints and on transit through gastric remnant and Roux limb in 24 such patients. Thirteen of them had slow gastric emptying and 13 had stasis in the Roux limb (two patients had both). Symptoms and transit were evaluated before and after three weeks of treatment using a questionnaire and scintigraphy. Responding subjects continued therapy and were interviewed again after six months. Seven patients with slow gastric emptying and three patients with Roux-limb stasis had enduring symptomatic relief; all exhibited accelerated transit during therapy: mean half gastric emptying time in the seven patients with slow gastric emptying was 204 +/- 89 min before and 111 +/- 59 min during cisapride (P less than 0.05); mean percentage of radioactivity, emptied from the gastric remnant, which remained in the Roux limb at 60 min in the three patients with Roux limb stasis was 74 +/- 4% before and 25 +/- 10% during cisapride (P less than 0.05). In patients without symptomatic response, transit did not improve.with cisapride long-lasting symptomatic relief and improved transit is achieved in about 40% of patients with the Roux-en-Y syndrome.