The pituitary function of patients with Rathke's cleft cyst before and after surgery was investigated to clarify the significance of surgery and operative indications. The authors have treated 19 patients with Rathke's cleft cyst. There were panhypopituitarism in 2 patients (11%), amenorrhea and/or galactorrhea in 3 (16%), diabetes insipidus in 4 (21%), and visual disturbance in 9 (47%). All the patients underwent systematic endocrinological examination and were found to have various degrees of pituitary dysfunction. Panhypopituitarism was endocrinologically confirmed in 2 patients. Hyperprolactinemia was observed in 4. These patients underwent aspiration of the cyst contents and biopsy of the cyst wall. Postoperative follow-up endocrinologic evaluation performed more than 3 months after surgery showed improvement in pituitary function in 9 out of 13 patients (69%). Amenorrhea and/or galactorrhea recovered or improved in 100% of patients and visual disturbance improved in 89%. However, diabetes insipidus and panhypopituitarism did not improve postoperatively, in any patient. The results of the present study indicate that the incidence of pituitary dysfunction in patients with Rathke's cleft cyst is higher than suspected and in most cases surgical intervention improves pituitary function and the clinical status of the patient. Therefore, surgical treatment is recommended even when the patient has only mild symptoms or signs, including pituitary dysfunction, to prevent irreversible panhypopituitarism.