BACKGROUND: 3,855 patients undergoing Roux-en-Y gastric bypass for morbid obesity between 1988 and 1994 are presented. METHODS: All patients were sent a standard questionnaire reflecting current weight, intervening complications and general health status and 1039 patients responded. Information gleaned from review of these questionnaires and a review of individual charts provided the data for this study. RESULTS: Average weight loss at 1 year was 46 kg and at 5 years was 34.5 kg. Operative mortality was 0.18%. Surgical morbidity rate was 3.4%. Average length of stay for patients hospitalized in 1994 was 3.6 days. The average operating time during that same year was 78 min, and the average hospital charges were $7250. CONCLUSIONS: Roux-en-Y gastric bypass can be performed with relative safety and acceptable morbidity. There is a demonstrable weight loss benefit which is maintained in the majority of patients over a period greater than 5 years. The expense and consumption of provider services are modest, and this procedure remains an excellent alternative for weight control among morbidly obese individuals.