Background: Nasal polyposis is a common problem. Since allergic fungal sinusitis (AFS) can present with unilateral or bilateral nasal polyps, it is important to be aware of the prevalence of AFS in patients with nasal polyps. This study was planned to evaluate the frequency of allergic fungal sinusitis. In the literature published nationally and internationally lies a controversy as they have stated variable results. This study may help all the clinicians to decide a good strategy if a high frequency of allergic sinusitis is noted in cases with nasal polyps. Objective: The objective of this study was to: determine the prevalence of allergic fungal sinusitis among patients with nasal polyps presenting in a tertiary care hospital Duration of the study: From: 02-04-2017 to 05-10-2017 Study Design: Cross sectional study Methodology: The patients fulfilling the inclusion criteria were enrolled after informed consent from OPD of ENT department Sheikh Zayed Hospital and FPGMI, LHR by the researcher. All patients with nasal polyps were advised CT scan and Paranasal sinuses with FESS protocol to be done from Radiology department of samo institution. Findings of allergic fungal sinusitis were noted (as per operational definition). All information was gathered by a performa (attached). Results: In our study, out of 100 cases of nasal polyps, 72%(n=72) were between 15-50 years of age while 28%(n=28) were between 51-70 years of age, mean+sd was calculated as 41.1+12.67 years, 55%(n=55) were females while 45%(n=45) were male patients, frequency of allergic fungal sinusitis among patients with nasal polyps was recorded in 18%(n=18) of the cases. Conclusion: We concluded that the frequency of allergic fungal sinusitis is high among patients presenting with nasal polyps presenting in a tertiary care hospital. So, it is recommended that every patient who present with nasal polyps, should be sort out for allergic fungal sinusitis. However, it is also required that every setup should have their surveillance in order to know the frequency of the problem. Keywords: Nasal polyps, allergic fungal sinusitis, frequency