BACKGROUND In recent times, due to advancement in sinus endoscopes and sinus surgery instruments and the acquirement of skills, the variety of sinonasal diseases being treated and the indications for transnasal endoscopic approaches have increased dramatically. They include chronic rhinosinusitis and sinonasal polyposis to sinonasal tumours, skull base and orbital pathology. We wanted to study the role and outcome of endoscopic sinus surgery in the management of sinonasal disease. METHODS A cross sectional study was conducted among 200 patients attending the Department of ENT, Govt. Medical College, Kozhikode, over a period 2 years with sinonasal diseases. Demographic details, ENT examination, CT scan Paranasal Sinuses (PNS) and endoscopic examination of the nasal cavity were performed in all patients. Clinical signs were recorded and classified according to their pathologies. All the patients were subjected to functional endoscopic sinus surgery. Operative methods and results were recorded. RESULTS Among the 200 patients, 144 (72 %) were males and 56 (28 %) were female patients in the present study. Among the 200 patients, 126 (63 %) were in the age group of 21 to 50 years. 40 / 200 (20 %) patients belonged to the age group of 0 to 20 Years. 34 / 200 (17 %) patients belonged to the age group of 51 to 70 years. CONCLUSIONS The diseases of the nose and paranasal sinuses ranged from inflammatory aetiology to neoplasms. Use of conventional tools for diagnosis and management of such a variety of diseases had their own limitations and demerits. Whereas endoscopic view of the disease sites was exceptionally clear and well-illuminated, giving an added edge to the ability to inspect the recesses with angled distal endoscopes. Definition of micro anatomical sites was well defined by the CT scan especially around osteo-meatal complex, and its anatomical variants. Functional endoscopic sinus surgery was an excellent and safe procedure. The prognosis in surgically treating sinonasal pathologies with FESS was good in terms of lesser morbidity and minimal chances of recurrence. KEYWORDS Sinusitis, Endoscopic Sinus Surgery, CT Scan PNS, Skull Base Surgery, Sinonasal Tumours