The efficient mechanism of cleaning the upper airway tract is the main condition of treatment the laryngological diseases. Proper drainage of nasal cavities and paranasal sinuses is based on two mechanisms: secretion and transport. All kinds of changes (inflammation, anatomical) which disturb normal function of nose and paranasal sinuses specially in the osteo-meatal region lead to chronic rhinosinusitis. Computer tomography takes an important place in the diagnosis of the chronic rhinosinusitis and is a kind of topographical map of important anatomical structures for save endonasal operations. Functional endoscopic sinus surgery (FESS) is the treatment of choice in chronic rhinosinusitis. From 2000 to 2006 in the Departent of Otolaryngology and Laryngological Oncology in Poznan 1075 FESS operations have been performed. During operations microscop, endoscops or both technics were used. An importance place took the postoperative treatment to reach the best results in every case.