BACKGROUND: Primary empty sella syndrome (PES) is thought to arise from an incompetent diaphragma allowing progressive herniation of arachnoid membrane with secondary compression and atrophy of the pituitary gland. As a consequence of the improvement and widespread use of neuroradiological techniques, such as computerized tomography (CT) and magnetic resonance imaging (MRI), empty sella is more frequently disclosed. The aim of this study is to assess the associated clinical characteristics and endocrinologic disturbance in empty sella syndrome. METHODS: From January 1986 to June 1996, 171 patients with empty sella syndrome have undergone analysis for clinical characteristics and associated disease. RESULT: In our study, PES was diagnosed in 131 of the 171 patients (77%). Primary empty sella syndrome was frequent in middle aged women (female:male 115:16, mean age: 50.6+12.6 years). The common clinical features were headache (80.2%), obesity (72.5%), and hypertension (27.5%). Most of patients with PES have normal pituitary function (75%). The frequent pituitary dysfunction was hyperprolactinemia in PES (21%). Partial and total emptiness of sella on sella CT or MRI were in 111 (84.7%) patients, and in 20 (15.4%) patients, respectively. The most common associated disease with empty sella syndrome was pituitary adenoma. CONCLUSION: PES should be considered as a possible cause in obese middle aged women with unexplained headache. The combined pituitary function test should be considered for evaluation of pituitary dysfunction when clinically suspected.