There has been an increasing body of research literature suggesting a seasonal pattern of mood fluctuations and eating behavior in bulimic patients. Fornari et al. [5] reported worsening of bulimic symptoms during winter. There is a logical connection between Seasonal Affective Disorder (SAD) and bulimia nervosa as both show increased appetite and carbohydrate craving and probably share a common neurobiologic abnormality such as serotonergic dysfunction. The aim of this study was to determine the prevalence of SAD in a sample of 259 consecutively evaluated outpatients admitted to an eating disorders clinic (254 women and 5 men). Eating disorder diagnosis was established on the basis of DSM-III-R criteria, and a modified version of the Seasonal Pattern Assessment Questionnaire was used to determine seasonality among patients. The sample was comprised of the following: 53.7% bulimics, 27.4% anorexics, 15.1% were classified as having an eating disorder not otherwise specified, and 3.9% had a diagnosis other than an eating disorder. The results indicated that 27.0% of the eating disorder patients met criteria for SAD. Of this group, 86 (71.4%) were bulimic, 35 (18.6%) were anorexic, and 20 (10.0%) were nonspecified. Details and additional findings are discussed.