In this study we describe the frequency of eating disorders (EDs) in a group of bipolar (BP) patients. We evaluated a sample of 51 outpatients, diagnosed as having BP I disorder on the basis of the Structured Clinical Interview for DSM-IV (SCID). Each of these subjects was administered the Binge Eating Disorder Clinical Interview (BEDCI) to determine the presence of binge eating disorder (BED) or bulimia nervosa (BN). Of the 51 BP patients, 14 (9 BED, 5 BN) met criteria for an ED. Most patients developed binge eating coincident with the first episode of BP disorder or after the onset of it. This was true for those who developed BED as well as BN, and involved both manic and depressive phases. All BN patients were women (5/5), and family history of binge eating was present in 80% of BN subjects, but only in 22.2% of BED and 29.7% of non-ED BP patients. We found a high frequency of concordance between BP illness and binge eating problems in our sample of BP patients. Given the temporal sequence of the mood disorder, which generally preceded the ED, we suggest a model in which the ED evolves due to modulation of emotions with food, as well as use of medications to treat BP disorder that disrupt hunger and satiety mechanisms. Given differences in gender distribution and family history, cultural and familial influences may also be significant in the minority of BP binge-eating patients who develop BN.