In this study we examined whether obese women with binge eating disorder (BED) reporting earlier onset binge eating differed from those with later onset binge eating on salient clinical parameters. Subjects were 112 women who sought treatment for BED. Subjects with early (< or = age 18) and later onset (> age 18) did not differ in age, weight, body mass index, or severity of binge eating. Participants were interviewed using the Eating Disorder Examination (EDE) and the Structured Clinical Interview for DSM-III-R, and completed a weight and diet history questionnaire. Early-onset binge eaters were more likely than those with later-onset to binge-eat before dieting, to have early onset of obesity and dieting, to have longer binge-free periods, and more paternal obesity and binge eating. Early-onset binge eaters also reported more eating-disorders psychopathology, and they were more likely to report a lifetime history of bulimia nervosa and DSM-III-R mood disorder. These data suggest that there are marked differences among BED patients presenting for treatment. Further research is needed to determine whether these differences reflect a different etiology or have implications for treatment.