Background: as a consequence of antigenic stimulation associated with chronic inflammation, the adenoids may enlarge so that they may almost fill the nasopharynx. Moreover, adenoid hypertrophy and allergic rhinitis can co-exist in the same patient and treating allergy may relieve patient's symptoms and thus avoid unnecessary surgery. Objective: this study aimed to determine the relationship between adenoid hypertrophy and allergic rhinitis in children based on clinical examination, nasal endoscopy and skin prick test. Methods: this was a prospective study included 50 children who were selected from many patients attended Otolaryngology Outpatient Clinic in Al-Azhar University Hospitals during the period from February 2018 to June 2018. All patients were signed an approved informed consent form before study enrollment. Results: the results of this study showed that there was no significant association between allergy and nasal obstruction neither measured by endoscopy, nor FRS. Furthermore, there was a significant negative correlation between allergy and adenoid volume measured only by endoscopy not by lateral X-ray nasopharynx. Supplementary, among all tested allergens, house dust and cotton dust allergy showed a significant negative association with the volume of adenoid. Moreover, all types of food and perennial allergens did not show significant correlations. Conclusion: this study showed that large adenoid may be associated with absence of allergy, whereas large turbinates may be associated with small adenoid. These findings may be helpful in clinical management of a child with nasal obstruction, so a detailed evaluation of the nose and nasopharynx is mandatory in each child with this complaint and it should be performed by nasal endoscopy. Consequently, the treatment should be geared toward the specific findings in that individual.