Objective To study the distribution of rifampin(RFP), isoniazid(INH) and pyrazi-namide(PZA) in the focus of spinal tuberculosis in order to provide the regimen of chemotherapy and surgi-cal treatment of spinal tuberculosis. Methods Twenty-four patients with spinal tuberculosis were divided into sclerotic group or non-sclerotic group according to the radiographic features of lesion. All patients re-ceived chemotherapy with 2SHRZ/2.5 H2R2Z2 for a duration of 4.5 months. 4 weeks after chemotherapy, all patients underwent surgery and specimen of serum, ilium and vertebral tissues including sclerotic wall, sub-normal osseous tissue, focus inside sclerotic wall (sclerotic group) and destructive focus, peripheral subnor-mal osseous tissue (non-sclerotic group) were obtained during operation at 120-130 and 180-190 minutes after oral intake in the morning respectively. The levels of 3 drugs in the specimen were measured using HPLC method. Results 1) The concentration levels of INH and PZA in serum were similar to the data in the literature, but the level of RFP was only 75% of that in the literature. The levels of 3 drugs in osseous tissue were significantly less than those of blood. 2) Concentrations of isoniazid and rifampicin in self-control ilium and sub-normal bone tissue were within or exceeded the bactericidal concentration values,and pyrazi-namide was five fold of it's minimal inhibitory concentration (MIC) in acid cellular condition. There were no significant differences between sub-normal bone and self-control ilium of 3 drugs concentration. 3) Concen-tration of 3 drugs in sclerotic bone wall were approximate to MIC respectively in sclerotic group and much lower than sub-normal bone. There was no drug distribution of focus inside sclerotic bone wall. 4) RFP and PZA in focus of non-sclerotic group corresponded to the levels of MIC respectively, though much lower than in other parts of vertebral tissues, but the INH in focus was of bactericidal level. Conclusion The sclerotic bone of affected vertebra plays an important role to block the drug's penetration into tuberculosis focus.