The incidence of current or lifetime affective disorder and borderline personality characteristics were measured in bulimia nervosa patients. The relationship of these variables to the severity of eating disorder symptomatology (Eating Disorder Inventory [EDI]) and general psychiatric symptoms (Hopkins Symptom Checklist [SCL]) was examined. Categorical diagnostic assessments of affective disorder and borderline personality disorder (BPD) were made by Structured Clinical Interviews for DSM-III-R (SCID-I and -II). Affective disorder diagnosis (both current and lifetime) strongly influenced EDI and SCL profiles, while borderline personality characteristics had little influence. An understanding of the broad psychological symptomatology in bulimics requires the consideration of comorbid psychiatric illnesses, especially affective disorders.