With liver biopsy materials obtained from 28 cases out of the 54 patients receiving pulmonectomy and being given blood transfusions after chemotherapeutic treatment for pulmonary tuberculosis, functional and histological studies of the liver were carried out with lapse of time, and the results are summarized briefly as follows. For those cases showing the GPT, GOT, and BSP level over 100 gamma/ml (89 Karmen units), 60 gamma/ml (83 Karmen units), and 10% respectively, it is consistent with diagnosing them clinically as the cases of post-transfusion hepatitis in view of their histological findings of the liver. If judged under the above-denoted criteria for diagnosis, three out of six nonicteric cases were not to be recognized as hepatitis. Of three parameters - the serum GPT and GOT levels and BSP clearance, even one of these set below the level above-indicated, was not to be available because of the increasing possibility to result in an erroneous diagnosis. The GPT level of 100 gamma/ml serves well as a screening test of post-transfusion hepatitis, but there is a pitfall of erroneous over-diagnosis in the period of less than one postoperative month. The GOT level of 60 gamma/ml is higher than the standard one so that it is possible for the cases of mild non-icteric hepatitis often being missed. Since the judgement depending only on the criteria of the BSP level is possibly prone to cause us either to overdiagnosis, or to under-diagnosis the hepatitis lesion, it is desirable to refer simultaneously to the GPT and GOT levels. In the diabetics the serum GPT, GOT and BSP are all apt to rise to abnormally higher levels than to be expected from the biopsy findings. Within one post-operative month the functional test values of the liver occasionally showed an abnormal rise, due possibly to an operative injury. In addition a transient, post-operative rise in the levels of these transaminases proved to be attributed to same infective complication of operation. The incubation period of the disease we studied, ranged from six to twenty weeks-most frequently in the period between six and ten weeks. The incidence of the disease was 51.3% and 53.5% on the bases of biopsy findings and clinical illness respectively, and appeared to be higher than formerly described. Of the cases we studied sequentially there were some cases where the disease had progressed in a short course of their illness to evolve into chronic hepatitis, or even to cirrhosis.