Objective: To investigate the characteristics of the electron encephalogram (EEG) of the sella turcica region tumor (STRT). Methods: Two hundred and 24 patients with STRT, confirmed by surgery, pathology, CT or MRI, were divided into 3 groups: (1) Pituitary adenoma (153 cases). (2) Craniopharyngioma(46 cases). (3) Other tumors in sella turcica region (25 cases). EEG were recorded with conventional method 2-30 days before operation. Results: Over half of the patients (56.7%) had normal or mild abormal EEGs. The rest of the patients had diffuse abnormal EEGs (29.0%), paroxysmal abnormal EEGs (8.5%) or local abnormal EEGs(4.9%). 24 cases displayed intermittent rhythmic delta activities (IRDA, 10.7%). Seventy-seven cases showed an inhibition of physiological waves. IRDA and inhibition of physiological waves frequently appeared in the EEGs of the craniopharyngioma group. The rate of the abnormality of EEG in the patients with large tumor (D>2 cm) was higher than that of the patients with small tumor (D<2 cm). Conclusion: Non -specific changes in EEG are the predominant manifestations in STRT. The main characteristics of the abnormal EEGs in STRT are diffuse or paroxysmal abnormality. Only a few cases have local abnormal EEGs. The extent of abnormality in EEGs correlates to the size of tumor. EEG is helpful in qualitative diagnosis of STRT