Abstract: The blastic transformation of aplastic aneamia into erythroleukemia is uncommon.Three patients,aged 30—56 years（0.98%）were found in our hospital in 305 patients with aplastic aneamia.The clinical course in these three patients lasted about 6—21 years before transformation. Erythroleukemia was diagnosed 3—15 years after the diagnosis of aplastic aneamia.The mechanism of transformation is discussed in brief.