This study explored variation in the decisions of primary care physicians to refer or not to refer obese patients to an endocrinologist and the principles underlying their decisions. Forty-five physicians—family practitioners, obstetricians, and general internists—made referral judgments on 24 cases and completed a questionnaire. Data indicated a difference among specialties in the number of cases referred (P≤ 0.01) that was not accounted for by physician characteristics. The number of cases referred ranged from 0 to 19, with a mean of 8. The patient's desire for treatment by an endocrinologist was overwhelmingly the major factor in decisions to refer. Gynecologists differed from other physicians by referring for management and not expecting the patient to return to their care. Referrals were not made primarily to rule out suspected endocrine disease or out of concern for morbidity due to obesity. These referrals are thus not perceived as medically beneficial, but are responses to patient pressure or physicians' desire to transfer management.