Purpose <p>To determine the relationships of tonsil and adenoid sizes with childhood allergic rhinitis.</p> Methods <p>The study was designed as cross-sectional. Children with allergic rhinitis were examined via endoscopic laryngoscopy, and their adenoid and tonsil sizes were measured. The frequency of allergic rhinitis symptoms, disease severity, and nasal symptom scores were compared.</p> Results <p>A total of 169 children diagnosed with allergic rhinitis were included in the study. The median age at diagnosis was 8&#xa0;years (range: 4–16), and 98 children (58.0%) were boys. Adenoid hypertrophy was observed in 125 (73.9%) patients, tonsil hypertrophy in 96 (58.7%) patients, and adenotonsillar hypertrophy in 81 (47.9%) patients. The disease was more persistent and severe in children with adenoid hypertrophy than in those without it (p = 0.045 and 0.013, respectively). Nasal symptom scores were higher in those with tonsil hypertrophy than in those without (p = 0.007). Scores were also higher in patients with adenotonsillar hypertrophy than in those with tonsillar hypertrophy alone and those without adenoid or tonsillar hypertrophy (p = 0.001).</p> Conclusions <p>Tonsil and adenoid sizes are associated with increased persistence, severity, and nasal symptom burden of disease.</p>