Introduction: Adenotonsillar hypertrophy (ATH) may present with growth retardation. Insulin-like growth factor 1 (IGF-1) mediates the anabolic effects of growth hormone (GH) on tissues. Most of the circulating IGF-1 molecules are bound to insulin-like growth factor-binding protein 3 (IGFBP-3). IGF-1 and IGFBP-3 serum levels reflect the levels of daily mean serum GH and are used as indices for evaluating the serum level of GH. This study aimed to determine the effect of adenotonsillectomy on IGF-1 and IGFBP-3 serum levels in patients with ATH or recurrent tonsillitis. Furthermore, we aimed to investigate the effect of adenotonsillectomy on growth indices such as weight and height. Materials and Methods: A total of 100 randomly selected children with a diagnosis of ATH or recurrent tonsillitis with a mean age of 10.2 ± 1.4 years (range, 3-17 years) were enrolled in the intervention group. Of those, 53 were boys and 47 were girls. The control group included 100 healthy children (62 boys and 38 girls) with a mean age of 8.5 ± 1.5 years (range, 4-15 years). Growth indices such as weight and height were measured and documented at the time of surgery and 6 months after the operation. Blood samples were taken preoperatively and repeated 6 months after adenotonsillectomy. The coated-tube immunoradiometric (IRMA) method was used to measure IGF-1 and IGFBP-3 levels. Results: Postoperative IGF-1 and IGFBP-3 serum levels as well as weight and height showed were significantly greater in comparison with preoperative measurements in both the intervention and control groups (P<0.001). At the end of study, the intervention group showed significantly greater changes from baseline in IGF-1 and IGFBP-3 serum levels, weight, and height in comparison with the control group (P< 0.001). Conclusions: This study shows that adenotonsillectomy in children with ATH or recurrent tonsillitis increases IGF-1 and IGFBP-3 serum levels in comparison with preoperative levels by affecting the GH-IGF-1 axis, and subsequently leads to a faster increase in growth indices compared with healthy peers during the same period.