A 30-year-old woman with Marfan's syndrome had chronic intractable headaches and spontaneous intracranial hypotension. The pain was concentrated over the occipitonuchal region, had elements of both migraine and tension headache, and was often aggravated by postural change. Myelography showed multiple, large, lumbosacral arachnoid diverticula. Radioisotope cisternography revealed a halolike accumulation in the lumbosacral region and rapid uptake of isotope in the urinary bladder, indicating cerebrospinal fluid leakage. Epidural blood patching brought immediate relief from the positional headaches. We concluded that patients with Marfan's syndrome and undifferentiated chronic headaches should be radiologically evaluated for spinal meningeal defects.