The objectives of this study were to determine the prevalence of Binge Eating Disorder (BED) and to investigate the subjective sleep qualities and the psychopathological features of BED in treatment-seeking obese patients. Thirty-six treatment-seeking obese subjects and 37 control subjects were interviewed with the DSM-IV research criteria for BED, The Pittsburgh Sleep Quality Index (PSQI), Bulimic Investigatory Test, Edinburg (BITE) and SCL-90-R scales. Eight out of 36 treatment-seeking obese patients (22.2 per cent) met the criteria for BED. The PSQI global scores, sleep latencies and SCL-PSDI, SCL-interpersonal sensitivity subscale results were all significantly higher in treatment-seeking BED obese subjects than non-BED (N-BED) subjects and controls. Our findings suggest that BED appears to be a common disorder in treatment-seeking obese patients. The treatment-seeking obese BED patients suffer from more psychopathological problems than N-BED obese patients and controls, and the subjective sleep qualities are likely to be disrupted in patients with BED. Copyright (C) 2004 John Wiley Sons, Ltd.