Objectives-To evaluate the clinical significance of lifetime eating disorder co-morbidity in a welldefined sample of patients with bipolar spectrum disorders and to describe cognitive correlates of disordered eating in this group.Method-Twenty-six bipolar patients with a lifetime history of a DSM-IV defined eating disorder (n = 17) or a clinically significant subthreshold eating disorder (n = 9) (ED group) were compared to 46 bipolar patients with no history of an eating disorder (No ED group) on demographic and clinical characteristics at study presentation, history of bipolar illness, and other psychiatric co-morbidity. Measures included the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), the Clinical Global Impression-Severity Scale-Bipolar Version (CGI-S-BP), and the Eating Disorder Examination (EDE). Height and weight were recorded to calculate body mass index (BMI).Results-Patients in the ED group were heavier and were rated as more symptomatic on the CGI-S-BP than were patients in the No ED group. The ED group also had a higher number of lifetime depressive episodes and greater psychiatric co-morbidity, excluding eating and mood disorders. Finally, after controlling for BMI and CGI-S-BP rating, patients in the ED group had significantly higher EDE Restraint, Eating Concern, Shape Concern, Weight Concern, and Global scores than did patients in the No ED group.Conclusions-These findings highlight the need for a renewed emphasis on the evaluation and management of weight and eating in the mood disorders. In particular, this research suggests that eating disorder co-morbidity may be a marker for increased symptom load and illness burden in bipolar disorder.