Background: Paranasal sinus diseases are one of the commonest causes of patients visit to an Otorhinolaryngologist. The symptoms are multiple and vague, while an examination is often limited as sinuses cannot be examined directly. Anterior rhinoscopy gives little information about middle meatus and osteomeatal unit. Objective: The study was carried out with an objective to compare the Diagnostic nasal endoscopic findings and radiological appearance in patients with paranasal sinus disease. Methods: This study included twenty four patients with chronic sinusitis resistant to medical treatment for a period not less than six weeks. The study work was done in Otorhinolaryngology Department in Zagazig University Hospitals for a duration from August 2016 to October 2017. Results: Patients' age ranged from 20 to 58 years with a mean of 32.6 ± 10.68. They were 6 males and 18 females. These patients were divided into two groups: The first group does CT 1-3 months before surgery. The second group repeats CT at the day before operation. Then detection of correlation between CT and intra operative endoscopy findings in both groups. Interpretation and conclusion: In our study, a high association is found between both the modalities of investigation  , i.e. CT scans and Diagnostic nasal endoscopy with one scoring over the other in different parameter. Diagnostic nasal endoscopy is found to be highly sensitive investigatory modality for parameters like frontal recess, spheno-ethmoid recess and hiatus semilunaris, whereas CT scan is found to be highly sensitive for parameters like maxillary sinus, uncinate process and posterior ethmoids. So, a case of sinus disease should be diagnosed as early as possible using both these modalities as together they complement each other. Early diagnosis and effective management cures the pathology and prevents disastrous complications.