The aim of the present study was to determine whether anorexia nervosa (AN), bulimia nervosa (BN) and obsessive-compulsive disorder (OCD) share clinical and psychopathological traits. The sample consisted of 90 female patients (30 OCD; 30 AN; 30 BN), who had been consecutively referred to the Department of Psychiatry, University Hospital of Bellvitge, Barcelona. All subjects met DSM-IV criteria for those pathologies. The assessment consisted of the Maudsley Obsessive-Compulsive Inventory (MOCI), Questionnaire of obsessive traits and personality by Vallejo, Eating Attitudes Test-40 (EAT-40), Eating Disorder Inventory (EDI), and Beck Depression Inventory (BDI). ANCOVA tests (adjusted for age and body mass index) and multiple linear regression models based on obsessive-compulsiveness, obsessive personality traits and perfectionism, as independent variables, were applied to determine the best predictors of eating disorder severity. On ancova several significant differences were found between obsessive-compulsive and eating-disordered patients (MOCI, P < 0.001; EAT, P < 0.001; EDI, P < 0.001), whereas some obsessive personality traits were not eating disorder specific. A total of 16.7% OCD patients presented a comorbid eating disorder, whereas 3.3% eating disorders patients had an OCD diagnosis. In the eating disorder group, the presence of OC symptomatology was positively associated (r = 0.57, P < 0.001) with the severity of the eating disorder. The results were maintained after adjusting for comorbidity. Although some obsessive-compulsive and eating disorder patients share common traits (e.g. some personality traits especially between OCD and AN), both disorders seem to be clinically and psychopathologically different.