OBJECTIVE To report 7 cases of acquired hemoglobin H in myelodysplastic syndromes. Clinical materials of the 7 cases were retrospectively presented. Clinical features of the similar cases in literatures were reviewed. The criteria for diagnosis of this entity by Steensma and its pathogenesis were discussed. CONCLUSIONS This entity is a new subtype of MDS with unique clinical features and pathogenesis, and might be a proper model in the study of MDS transformation.