The endoscopic sinus surgery has become a popular procedure in patients with chronic paranasal sinusitis and/or nasal polyps. But bleeding has been one of the most common problems in the endoscopic sinus surgery. Reducing the amount of bleeding, we analyzed the various factors which may influence intraoperative bleeding in 183 patients who underwent endoscopic sinus surgery from May of 1992 to November of 1993. The results are as follows : 1) There was no significant difference in intraoperative bleeding between children and adults(p>.05). 2) There was no significant difference in intraoperative bleeding between with and without preoperative medications(p>.05). 3) There was no significant difference in intraoperative bleeding between the patients with and without a history of previous sinus surgery of paranasal sinusitis or polyps(p>.05). 4) There was no significant difference in intraoperative bleeding between general and local anesthesia(p>.05). 5) There was significant difference in intraoperative bleeding among the extent of diseases(p<.05). 6) There was significant difference in intraoperative bleeding between Oxymetazoline and Cocaine local anesthesia(p<.05).