Purpose: Soluble transferrin receptor (sTfR) is a shortened extracellular form of the membrane transferrin receptor, which is produced by proteolysis. The concentrations of serum sTfR are related to the iron status and erythropoiesis in the body. We investigated whether the serum sTfR levels can be helpful for the diagnosis and treatment of children with iron deficiency anemia (IDA). Methods: Ninety-eight patients with IDA were enrolled. Patients were classified according to the age at diagnosis as follows: Group 1 (78 children aged 6-59 months), and group 2 (20 adolescents aged 12-16 years). Results: Serum sTfR levels had a negative correlation with hemoglobin (Hb), mean corpuscular volume, ferritin, serum iron, transferrin saturation; and a positive correlation with total iron binding capacity (TIBC) and red cell distribution width in group 1. Serum sTfR levels were not correlated with ferritin and TIBC, but they had a significant relationship with other iron indices in group 2. Hb and serum sTfR levels had a significant inverse relationship in both groups. But there was no correlation between Hb and serum ferritin in group 1. Serum sTfR levels decreased inversely following an increase in Hb after iron supplementation for 1 month in 30 patients of group 1. Conclusions: Serum sTfR levels were significantly correlated with the other diagnostic iron parameters of IDA, and were inversely related with the increase in hemoglobin after iron supplementation. Therefore, serum sTfR levels can be a useful marker for the diagnosis and treatment of IDA in children.