We describe 10 patients with idiopathic intracranial hypertension who did not have papilledema. Idiopathic intracranial hypertension without papilledema, although rarely reported, may well be a clinically important headache syndrome. Historical and demographic features of patients with idiopathic intracranial hypertension without papilledema are similar to those of patients with papilledema. Obese women with chronic daily headache and symptoms of increased intracranial pressure, pulsatile tinnitus, history of head trauma or meningitis, an empty sella on imaging studies, or a headache that is unrelieved by standard therapy should have a diagnostic lumbar puncture. Findings from laboratory and neurologic investigations are normal in most patients with idiopathic intracranial hypertension without papilledema. Initial management should include removal of possible inciting agents, weight loss if applicable, and standard headache therapy. Lumbar puncture and diuretic therapy should precede a trial of corticosteroids. Surgery (lumboperitoneal or ventriculoperitoneal shunt or perhaps optic nerve sheath fenestration) may be indicated for prolonged incapacitating headache that is not responsive to medical management or lumbar puncture.