PURPOSE: A composition containing ezatiostat or salt thereof and a method thereof are provided to treat myelodysplastic syndrome.CONSTITUTION: A composition for treating myelodysplastic syndrome contains the therapeutically effective amount of ezatiostat or salt thereof. The ezatiostat or salt thereof is ezatiostat hydrochloride. The daily dose of ezatiostat hydrochloride is 2g. The ezatiostat or salt thereof is administered in a tablet form.COPYRIGHT KIPO 2013본 발명은 골수이형성 증후군을 치료하기 위한 구체적인 치료 계획에 관한 것이다.