Vomiting is a frequent complaint after revisional gastric surgery using a Roux-en-Y biliary diversion. This is believed to be due to gastric stasis or stasis in the jejunal component of the Roux-en-Y. Thirty-three patients, ten with a satisfactory outcome following Roux-en-Y diversion and 23 with an unsatisfactory outcome, were studied using a semisolid, radiolabelled meal and compared with 12 normal subjects. Outcome was assessed by modified Visick grading. Seven patients with an unsatisfactory outcome because of frequent vomiting had gastric stasis and two had delay in emptying of the jejunal component of the Roux-en-Y. Vomiting was more likely in patients with a dependent sump (P less than 0.006) and emptying was significantly prolonged where a sump was present (P = 0.0009). Surgical technique contributed to the dependent sump.