Nasal mucocilliary function is one of the most important and indispensible mechanism of the respiratory tract providing protection against the atmospheric environment. So, mucocilliary function is well recognized as a first line of defense in the airway. The saccharin method is a simple and non-invasive way to measure the mucocilliary function of the nasal cavity and it is more reliable in the pathologic condition than other methods. So, it was thought to be the most suitable method for the presenting study. In chronic paranasal sinusitis, the mucocilliary flow is significantly slow and it is known to be improved by various type of therapy. We have tried to measure the saccharin transit time(STT) preoperatively and postoperatively for ninety four patients with chronic paranasal sinusitis who have undergone endoscopic sinus surgery, and these data were analysed. The preoperative STT was prolonged in patients with chronic paranasal sinusitis than normal control group and it was shortened at various postoperative periods. These data showed that impaired mucocilliary function in patients with chronic paranasal sinusitis was much improved after surgery gradually with healing process.