Objective:To study distribution of pancytopenia in 13 kinds of malignant hematological diseases.Methods:Analyzing peripheral blood cells in 655 patients with malignant hematological disease,evaluating proportion of patients with pancytopenia in all patients and their incidence rate respectively.Results:81 out of 655 patients were involved pancytopenia at preliminary diagnosis.Number of patients with pancytopenia in M4/M5,ALL,NHL,MF、M2 M7,M6,M1,CML,HCL,M0,M3 were in reducing.In myeloid diseases,the pancytopenia incidences of M0,MF,M1,M7,M6,M4/M5,CML,M2 and M3 were 75%,56%,50%,45%,33%,13%,9%,5% and 3% respectively.While,of lymphoid disease as HCL,MM,NHL and ALL were 50%,50%,36% and 6% respectively.Conclusions:Pancytopenia involved in malignant hematological disease was not only related with disease incidence,but also associated with disease entity and their pathological characteristics.