The major adverse reactions of antithyroid drugs are hematologic; aplastic anemia (AA) is one of the rarest and most severe complications. Use of recombinant human hemopoietic colony-stimulating factor was reported to be of benefit in patients who developed agranulocytosis, although there is still some doubt regarding the efficacy in AA. We present a case of a 58-year-old female patient with Graves' disease who developed AA in the third exposure to methimazole (MMI). The withdrawal of MMI and early treatment with 5 microg/kg per day recombinant human granulocyte colony-stimulating factor (G-CSF) for 9 days, allowed a favorable recovery of peripheral blood cell count. We conclude that the use of hemopoietic colony stimulating factors might be a suitable means to achieve the correction of severe thionamide-induced hematologic adverse reactions.