OBJECTIVE: The present study sought to determine the prevalence of obsessive-compulsive disorder among patients with eating disorders. METHOD: Ninety-three women who met DSM-III-R criteria for anorexia nervosa or bulimia nervosa were investigated by using a semistructured diagnostic interview, the Yale-Brown Obsessive Compulsive Scale, and the Eating Disorder Inventory. RESULTS: Thirty-four patients (37%) met the DSM-III-R criteria for obsessive-compulsive disorder and also had a clinically significant score of 16 or higher on the Yale-Brown scale. These patients also had significantly higher, and hence pathological, mean scores on five of eight Eating Disorder Inventory scales than patients with eating disorders without concomitant obsessive-compulsive disorder. CONCLUSIONS: These results suggest that there is a high prevalence of obsessive-compulsive disorder among patients with anorexia and bulimia nervosa and that this prevalence may be correlated with the severity of the eating disorder.