To determine the prevalence of night-eating syndrome in the general population and among a new sample of obesity surgery patients. Method: Night-eating syndrome was defined by presence of morning anorexia, excessive evening eating, evening tension and/or feeling upset, and insomnia. A randomly selected sample of 2,097 adults (survey sample) answered structured interview questions on night-eating syndrome. A self-report form was completed by 111 patients who had received gastric restriction surgery for obesity at a patient reunion (patient sample). Results: Prevalence of night-eating syndrome in the survey sample was 1.5% (31 of 2,097). Prevalence in the patient sample was 27% (30 of 111). Weights for subjects in each sample, with and without the syndrome, were comparable. Discussion: Prevalence of night-eating syndrome was higher in the patient sample than in the survey sample. Within each sample, presence of the syndrome was not related to weight. Prevalence in the survey sample was within the range reported for binge-eating disorder. Night-eating syndrome may warrant consideration as a distinct eating disorder. © 1997 by John Wiley & Sons, Inc. Int J Eat Disord 22: 65–69, 1997.