Binge eating disorder (BED) has been hypothesized to be associated with poor outcome in gastric bypass surgery (GBP). However, past studies have yielded inconsistent results regarding BED and surgical outcome, which may be due to the variety of measures used to assess BED. The present study examines the utility of two commonly used BED diagnostic tools: the Structured Clinical Interview (SCID) and the Questionnaire of Eating and Weight Patterns-Revised (QEWP-R). Subjects were 168 adult patients evaluated for GBP. BED was assessed using the SCID and the 27% of the sample received a diagnosis of BED using the QEWP-R, compared with 14% using the SCID. Agreement using Cohen's kappa was 0.37. Compared to sub-non-concordant diagnoses of BED, subjects with concordant diagnoses scored on a measure of self-esteem. Although both diagnostic tools use the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) criteria, each yielded different results. Further studies are needed to determine the most accurate method of assessing BED in this population.