Eighty-five patients with refractory transformed migraine type of chronic daily headache (CDH) had spinal tap as a part of diagnostic work-up. Twelve had increased intracranial pressure without papilledema, transient visual obscurations, or visual field defects. The headache profile of these 12 patients was not different from that of transformed migraine type of CDH. Acute headache exacerbations responded to specific antimigraine agents such as ergotamine, dihydroergotamine (DHE), and sumatriptan, whereas prophylactic antimigraine medications were only partially helpful. Addition of agents such as acetazolamide and furosemide, after the diagnosis of increased intracranial pressure, resulted in better control of symptoms. These observations suggest a link between migraine and idiopathic intracranial hypertension that needs further research. In refractory CDH with migrainous features, a spinal tap to exclude coexistent idiopathic intracranial hypertension without papilledema may be indicated.