OBJECTIVE To study the distribution of isoniazid and its metabolite in spinal tuberculosis following chemotherapy. METHODS Twenty-three patients with spinal tuberculosis received chemotherapy with 2SHRZ/16HRZ (for a total of 18 months). Four weeks after the chemotherapy, all the patients underwent surgery and specimens of the serum, ilium and vertebral tissue including the sclerotic wall, focus inside the sclerotic wall (if present) and destructed foci were obtained. CT was performed in all the cases to test the HU of the foci before operation, and the levels of isoniazid and its metabolite in the specimen were measured with high-performance liquid chromatography (HPLC). RESULTS The levels of isoniazid and its metabolite were the highest in the serum, followed by normal ilium and non-sclerotic bone, and were extremely low in the sclerotic wall and foci. Their levels in the non-sclerotic bone of the compromised vertebra and normal vertebra showed no significant difference (P>0.05), but in the sclerotic bone, their levels were significantly higher than in the normal vertebra (P<0.05). Isoniazid and its metabolite are hardly detectable in the sclerotic foci in the compromised vertebrae. CONCLUSION Isoniazid and its metabolite may reach therapeutic concentration in normal vertebra and nonsclerotic bones of the compromised vertebra, but not in the disease foci or the sclerotic bone of the compromised vertebrae.