This study surveys the extent and severity of haematological abnormalities which occurred in 380 patients with pulmonary tuberculosis. Full blood count, bone marrow aspiration smears, and bone marrow trephine biopsy was analyzed by authors. Anaemia was present in 32 percent of patients. Leucocytosis with neutrophilia occurred in 18 percent. Leucopenia with neutropenia, and lymphopenia was observed in 16 percent in patients with very severe clinical tuberculosis. Elevated platelet count occurred in 8 percent with deep vein thrombosis in legs in 50 percent. Dysmyelopoietic syndrome was diagnosed in one case by bone marrow trephine biopsy. There was a close correlation between the haematological abnormalities and the severity of clinical findings of pulmonary tuberculosis. This survey has revealed that haematological abnormalities are relatively common in severe pulmonary tuberculosis. It seems that body weight loss, white blood cell count, haemoglobin level and erythrocyte sedimentation rate are useful indices of severity of the tuberculosis. The return of these indices to a normal level is a good indication of disease control in that they correlate with sputum conversion to acid-fast bacilli negative.