Introduction: Sickle cell anemia (SCA) is a disease that develops episodes of acute pain and multiple organ dysfunction that can affect the GH/IGF-1 axis. The severity of SCA is influenced by modifying factors, such as levels of fetal hemoglobin (HbF), the co-inheritance of alpha-thalassemia, or treatment with hydroxyurea (HU). Objective: To evaluate in children with SCA, the association of modifying factors with growth and serum levels of IGF-1 and IGFBP-3. Methods: This cross-sectional study in children with SCA evaluated bone age (BA), adult height prediction (AHP) using BA, a target height (TH) calculated as the mean SDS of the parents, and laboratory parameters. Children were grouped according to serum levels of HbF, co-inheritance of alpha-thalassemia, and HU therapy. Results and Conclusions: The mean age of the 39 patients was 8.2±2.2 years old. The average height was -0.75±0.30 SDS, and 10.3% (4/39) had short stature. Adjusted levels of IGF-1 or IGFBP-3 were significantly higher in children with SCA under HU therapy for more than 1 year, in children with HbF levels >10%, and in those without alpha-thalassemia. Using SDS, the growth potential of children with SCA in relation to their parents, calculated by the difference between AHP and TH, as well as the difference between children’s height and their TH, were lower in children with co-inheritance of alpha-thalassemia. Therefore, the co-inheritance of alpha-thalassemia in children with SCA may represent an additional cause for impaired growth.