Rhinitis is aiheterogeneous disordericharacterized by one or more of the following nasalisymptoms: isneezing, iitching, irhinorrhea, and/or nasal congestion. iRhinitis frequently is accompanied byisymptoms involving the eyes, iears, andithroat, including postnasalidrainage. To evaluateithe expressioniof interleukin-17iin patients presentingiwithiallergic rhinitisiand nasalipolyposis. This Aicase-control study was conductedion total of 60 subjects at BenhaiUniversity and BenhaiTeaching Hospitals. They wereidivided into two equaligroups; the casesigroup which included 15 allergicirhinitis case, and 15 nasalipolyposis cases, and theicontrol group whichiincluded 30 healthyisubjects. All cases were subjected toicomplete historyitaking and thorough rhinologicaliexamination. In addition, iserum and tissueiIl-17 were measures for all cases, whereas only theiserum level was measured inicontrols. Expression ofiIL-17 was significantly upregulated iniNP patients and was more severe iniatopic patients. In addition, there wereisignificantly positive correlationsibetweeniIL-17 and clinical and histological features. Our study suggests an important role for IL-17iiniNP. Overall, we hopeithat present study would enable us to obtain a deeper insight into the pathogenesisiofiNP and provide a potential target for the treatment of NP. Based on our study results, increasediIL-17 serumilevels might be considered a marker ofiallergy severity iniallergic rhinitisiand nasalipolyposis patients. This implies that IL-17 mayibe one of theietiologies in the pathogenesis of bothiAR andiNP. Based on these results, we propose that IL-17icontribute to the developmentiof NP and have an impact on clinical severity.