Aims: Vitamin D has also been shown to reduce respiratory infections in children. The aim of this study was to investigate the relationship between serum vitamin D levels and tonsillar and adenoid hypertrophy in children. Instrument & Methods: This study was a retrospective cross-sectional study that was performed on 140 children with symptoms of tonsillitis referred to the hospitals of Tabriz University of Medical Sciences. All patients were divided into four groups according to the degree of tonsillitis and their severity of tonsillitis was compared with the serum level of vitamin D. Findings: Children were divided into four groups based on their grade level. There was no statistically significant difference in terms of gender between the four groups (p=0.845). The average level of vitamin D in children is as follows: Grade 1: Vitamin D level was 18.12±2.27 ng/dL; Grade 2 had vitamin D levels of 17.48±2.54 ng/dL; Grade 3 had vitamin D levels of 15.27±2.03 ng/dl, and grade 4 children had vitamin D levels of 15.01±2.12 ng/dL. Comparison of vitamin D levels in different groups was not statistically significant (p=0.557). Conclusion: There is no relationship between vitamin D levels and clinical signs and symptoms of tonsillitis in children.