Background: Allergic diseases are among the most common chronic conditions in pediatrics. Objectives: This study aimed to evaluate the relative frequency of allergic rhinitis (AR) in children with adenotonsillar hypertrophy. Methods: In this descriptive study, 175 patients with adenotonsillar hypertrophy referred to the Imam Khomeini hospital of Ahvaz from March 2019 to March 2020 were enrolled. Allergic rhinitis was diagnosed based on the Score for AR (SFAR) questionnaire. The questionnaire, including the expert-designed SFAR, has eight main components that evaluate eight quantitative features of AR, and each was designated with a specific weighted score based on previous clinical studies. The total score could vary from 0 to 16. Frequency and percentage were used to describe the data. The chi-square test and Fisher's exact test were used to analyze the data. Results: One hundred seventy-five patients with adenotonsillar hypertrophy in the age range of 1 to 17 years were studied. Ninety-one patients (52%) were male, and 84 patients (48%) were female. Based on the score obtained from the questionnaire, 146 patients (83.4%) had a score of less than seven, indicating susceptibility to AR. Twenty-nine patients (16.6%) had a score equal to or higher than 7, confirming the diagnosis of AR. The Chi-square test showed that AR was significantly associated with all the components of the questionnaire, except for cigarette smoking (P-value < 0.001). Conclusions: This study showed the strong association of AR with some demographic factors. Allergic rhinitis could potentially increase the risk of adenotonsillar hypertrophy in children.