Patients with eating disorders (ED) frequently exhibit additional psychiatric disorders. This study aimed to examine whether psychiatric comorbidity in ED patients is associated with increased severity of ED symptoms in a sample of 277 women with a current ED (84 anorexia nervosa, 152 bulimia nervosa, 41 eating disorders not otherwise specified). Psychiatric comorbidity of Axes I and II was determined using the Structured Clinical Interview (SCID) for DSM-IV. Severity of ED-related symptoms was assessed using interviewer-rated scales from the Structured Interview for Anorexia and Bulimia Nervosa (SIAB). Affective and anxiety-related disorders of both axes were linked with increased intensity of weight- and appearance-related fears and concerns. Frequency of binge-eating and frequency of purging both were associated with Axis I anxiety disorders, substance-related disorders, and Cluster B personality disorders. Frequency of dieting was related to anxiety disorders on both axes. Multivariate analyses revealed that Axis I anxiety disorders were more closely linked with severity of ED symptoms than affective or substance-related disorders. The results showed that psychiatric comorbidity of both axes is linked with increased severity of ED symptoms and that there are associations between specific ED symptoms and specific forms of comorbidity.