Consistent predictors of attrition in obesity treatment have not been identified. This study examined whether pretreatment psychological and health behavior variables would predict attrition from a 26 week clinical multidisciplinary VLCD and behavior therapy program. Higher levels of depression, current smoking, being sedentary, and having nontreated high blood pressure were associated with treatment attrition. Thus, a biopsychosocial assessment which evaluates medical and psychiatric status may help clinicians to identify individuals at high risk for attrition.