Abstract: Objective To study the application of immature platelet fraction（IPF）detected with automated XE-5000 in diagnosis of hematological diseases. Methods Percentage of reticulated platelets（RP）,absolute value of IPF and mean platelet volume（MPV）were detected with automated XE-5000 in 35 patients with idiopathic thrombocytopenic purpura（ITP）,in 28 patients with aplastic anemia（AA）,in 40 patients with acute leukemia（AL）,and in 24 patients with chronic granulocytic leukemia,respectively. Results The percentage of RP in patients with ITP and the MPV in patients with CGL were significantly higher than those in normal controls（P＜0.05）.The absolute value of IPF was higher in patients with AA and in those with AL and lower in patients with ITP than in normal controls with no significant difference（P＞0.05）. Conclusion IPF in peripheral blood can reflect the amount of platelets produced by megakaryocytes,thus contributing to the diagnosis and differential diagnosis of hematological diseases.XE-5000 is a practical and valid device for the detection of IPF.