Tuberculosis has now become a curable disease with chemotherapy. So it is natural that the present issues in tuberculosis management are focused on how to complete standard chemotherapy. In this context, management of adverse effects constitutes an essential part of antituberculosis chemotherapy, as well as directly observed therapy. In this symposium, discussions were held about three major subjects on this issue. First, hepatotoxicity develops frequently and has sometimes fatal outcome, which makes it the most problematic adverse effect. "Management of hepatotoxicity during antituberculosis chemotherapy" was published by the Japanese Society for Tuberculosis (JST) in 2006. Dr. Shinsho Yoshiba evaluated this recommendation and pointed out that the criteria for discontinuation of drug based on AST, ALT and bilirubin levels is too sensitive and the concept of predicting fulminant hepatic failure (FHF) is lacking. He stressed the importance of monitoring serum prothrombin time for predicting FHF. Next, allergic drug reaction such as fever or skin rash often causes distress, although rarely fatal. As isoniazid (INH) and rifampicin (RFP) are key drugs for the cure, readministration of these drugs is often attempted by desensitization therapy. "Recommendation about desensitization therapy of antituberculosis drugs" was also published by JST in 1997. Dr. Yoshihiro Kobashi reported high success rates of 79 percent for INH and 75 percent for RFP according to this recommendation. He also reported correlated factor with the success, such as the longer period from the discontinuation to the desensitization therapy and lower doses of drugs at starting desensitization. Finally, we sometimes experience transient worsening of radiographical findings and general symptoms during antituberculosis chemotherapy. This is presumed to be due to allergic reaction to dead bacilli without requiring discontinuation of the drug. Differential diagnosis includes drug-induced pneumonia requring discontinuation and true worsening of pulmonary tuberculosis due to drug resistance requiring change in therapy. Dr. Masanori Akira reported that presence of ground-glass attenuation and/or consolidation by HRCT suggests transient worsening or drug-induced pneumonia, whereas presence of centrilobular nodules and/or tree-in bud suggests true worsening. We believe that these findings from the symposium will add useful information for management of adverse effects and be helpful for implementation of antituberculosis chemotherapy. (1) Hepatotoxicity of antituberculosis drugs: Shinsho YOSHIBA (Sempo Tokyo Takanawa Hospital) Antituberculosis drugs are sometimes hepatotoxic. Doctors who are responsible for the treatment of patients with tuberculosis should always be aware of their hepatotoxicity, because it seldom leads to fulminant hepatic failure. The Japanese Society for Tuberculosis proposed criteria based on the levels of AST, ALT and bilirubin for the prevention of such grave hepatic injury in 2006. In recent years attempts have been made to predict fulminant hepatic failure (FHF) before patients develop coma. Yoshiba's formula using prothrombin time, etiology, cholinesterase and bilirubin is widely accepted as useful to predict FHF. Introduction of the formula to this area is recommended. (2) Desensitization therapy for allergic reactions of antituberculous drugs: Yoshihiro KOBASHI, Mikio OKA (Division of Respiratory Diseases, Department of Medicine, Kawasaki Medical School) We evaluated the usefulness of desensitization therapy for patients showing allergic reactions of INH and RFP according to the guideline proposed by the Japanese Society for Tuberculosis. Adverse reactions were 22 patients with drug eruption, 22 with drug fever and 6 with drug fever plus eruption. The clinical effect of desensitization therapy was good in 27 out of 36 patients for RFP (75%), and in 19 out of 24 patients for INH (79%). The comparative study between patient group with success desensitization therapy and that with failure desensitization therapy was not a significant difference except for initiation period of desensitization therapy. (3) The imaging features of early transient radiographic progression, true worsening of TB, and drug induced pneumonitis during TB treatment: Masanori AKIRA (Department of Radiology, NHO Kinki-chuo Chest Medical Center) HRCT findings of the new lesions in the early transient radiographic progression are enlargement or confluence of the original lesions, development of areas of ground-glass attenuation and/or consolidation ipsilateral to the original lesion, and development of areas of ground-glass attenuation and/or consolidation in the subpleural region contralateral to the lesion. These CT findings may suggest a local hypersensitivity reaction to drug or massive dead tubercle bacilli per se. In contrast, CT findings of patients with multiple drug-resistant tuberculosis and true progression are centrilobular nodules, tree-in-bud appearance, nodules, and cavitation. These CT findings may suggest a bronchogenic spread from the original tuberculous lesions.