Transsphenoidal approach(TSA) is the most safe and effective approach to the pituitary lesion3). This technique inevitably provokes mucosal damage of the sphenoid sinus and results in postoperative change in the sphenoid sinus. There has been few report about postoperative sphenoid sinus change in Korea. We analyzed CT and MRI findings of the 51 patients who had undergone transseptal transsphenoidal surgery at the Kangnam St. Mary's Hospital from 1990 to 1995 retrospectively and compared the postoperative radiological findings with the preopertative findings. We divided the subjects into three group. Group 1 is scans that were checked within four weeks postoperatively. Group 2 is those checked between four weeks and six months postoperatively and group 3 is those after 6 months postoperatively. All 37 scans of group 1 were abnormal, 16 of 19 were abnormal in group 2 and 25 of 39 were abnormal in group 3.