ISONICOTINIC acid hydrazine (INH) is one of the drugs presently used in the treatment of tuberculosis. Toxic reactions of this drug, usually mild, have been estimated to occur in 5 per cent of patients.1The most common type of reaction is an effect upon the central nervous system and the production of peripheral neuropathies.2Less commonly, dermatitis, drug fever, leukopenia, purpura, and jaundice have been reported.1As of 1960 6 cases of jaundice suspected of being due to INH in patients receiving average therapeutic doses have been reported.2-6In all of the reported cases, other potentially hepatotoxic antitubercular drugs such as streptomycin and/or para-aminosalicylic acid (PAS) were also given, making the final evaluation difficult. This report describes a case of fulminating submassive necrotic hepatitis associated with isoniazid administration. Report of a Case First Admission.— A 50-year-old Negro male was first admitted to the Veterans Administration Hospital,