Introduction: This prospective interventional study was carried out to compare the effect of Endoscopic Sinus Surgery on Chronic Rhinosinusitis as compared to Nasal Polyposis Materials & Methods– Sample size were 70 ( patients attending ENT OPD of a tertiary care hospital in Kolkata ,India from August 2014 to July 2015, aged between 18–65 years, among them 44 were CRS and 26 were NP. The parameters studied were – pre and post–operative assessment of symptom severity score, preoperative Lund Mackay CT scan score, pre and postoperative Lund Kennedy nasal endoscopy score. Results– The cases were followed up to 18 months. In our study both the groups showed significant improvement after ESS with the symptomatic improvement of NP group reducing on long follow up. Conclusion– ESS is equally effective in both Chronic Rhinosinusitis and Nasal Polyposis patients that means the effect of difference of outcome of ESS on CRS and NP is not statistically significant.