Twenty-four patients with the clinical diagnosis of pseudotumor cerebri were studied. There were 11 male and 13 female patients, mean age at presentation 31.4 years. Duration of symptoms before the admission to hospital ranged from 10 days to 2 years. The symptoms in order of frequency, were headache, visual impairment and diplopia. Coexisting pathologic and medical conditions were Behcet's disease in 5, empty sella in 3, and hypothyroidism, oral contraception, obesity, pregnancy, anemia, polycythemia, corticosteroid use, late onset congenital adrenal hyperplasia, menstrual irregularity and meningioma in one patient each. Magnetic resonance venography showed normal findings in 4 patients with Behcet's disease, and one had normal cerebral magnetic resonance imaging but did not undergo venography. The incidence of Behcet's disease in patients with pseudotumor cerebri and without signs of cerebral venous thrombosis is unusually high. Therefore, we believe that patients with pseudotumor cerebri should be investigated for Behcet's disease, particularly those who are considered for shunt operation.