Sinusitis in its simplest form is an inflammation of the mucous membranes of the sinuses. It is a common condition in medical practice, which affects many people worldwide and its prevalence is rising. Rarely the disease may involve other parts of the sinus (bone) or the surrounding structures (nose, orbit and, central nervous system) before the patient consults doctors. The three important factors on to which the pathophysiology of the sinus disease is related are: the patency of the ostia, the function of the cilia and the quality of the nasal secretions. Of the three factors, the patency of the ostia is the most important in the development of CRS. The diagnosis of CRS relies on clinical judgment based on a number of subjective symptoms and few findings in physical examination, so it was necessary to perform complementary exams in order to confirm diagnosis and also to indicate severity and origin of the disease. So CT scan and nasal endoscopy were performed. CT of the nose and paranasal sinuses is the ideal imaging exam to study nasal and paranasal sinuses diseases. It has high sensitivity because it provides precise information about soft tissue and bony parts of the nasal cavity, paranasal sinuses, orbit. Nasal endoscopy is mentioned as a standard test to precisely assess nasal obstructive disease. Nasal endoscopy enhances the sinonasal evaluation by allowing visualization of anatomy that is not possible with anterior rhinoscopy. It produces a closer inspection of the involved areas, as well as the opportunity for directed culture or biopsy. ESS has evolved as an effective treatment option, and indeed, is the treatment of choice for medically refractory CRS with or without polyps, with excellent success rates.