BACKGROUND: Tuberculosis has commonly been associated with various hematologic changes. A difference between the changes found in pulmonary tuberculosis and those found in miliary tuberculosis has been discussed. Up to now some worker were investigated hematological changes associated with pulmonary tuberculosis but was not investigated those associated with miliary tuberculosis in korea. Therefore we examimed the peripheral blood and bone marrow findings in miliary tuberculosis patients to determine hematologic changes. METHODS: We performed blood sample at admission and bone marrow biopsy within 7days after admission. For evaluation of the hematologic findings, full blood counts and marrow differential counts were defined by the criteria outlined by Dacie and Lewis2). RESULTS: 1) Peripheral blood findings: Pancytopenia in 10% of patients, anemia in all patients, leukocytosis in 10% of patients, leukopenia in 20% of patients, thrombocytopenia in 30% of patients, lymphocytopenia in 90% of patients, monocytosis in 40% of patients and neutrophilia in 10% of patients were found at peripheral blood. 2) Bone marrow findings: Lymphocytopenia in 30% of patients, lymphocytosis in 20% of patients, plasmacytosis in 40% of patients, monocytosis in 100% of patients, and hypocellularity in 30% of patients were found at bone marrow. Erythropoiesis was decreased in 30% of patients. Granulopoiesis was decreased in 20% of patients and increased in 20% of patients. Bone morrow granuloma occured in 25% of patients. CONCLUSION: Hematologic changes of miliary tuberculosis were seen tendency of cytopenic pattern but monocyte was increased at peripheral blood and bone morrow. This findings would provide additional information for the differential diagnosis of miliary tuberculosis.