Serum erythropoietin (EPO) and granulocyte-macrophage-colony stimulating factor (GM-CSF) levels were determined in 12 children with acute and seven with chronic idiopathic thrombocytopenic purpura (ITP) prior to and during megadose methylprednisolone (MDMP) treatment by using enzyme-linked immunosorbant assay (ELISA) kits. It was shown that elevation of EPO and GM-CSF levels was correlated with an increase in hemoglobin (Hb), packed cell volume (PCV), red blood cell (RBC), leukocyte (Leu), polymorphonuclear leukocyte (PMN) and monocyte (Mo) counts during MDMP treatment.