This is a preliminary report on the bacteriological examination of specimens which were obtained directly from the tuberculous lesions during operations. Among the 25 cases which had been clinically diagnosed as bone and joint tuerculosis from September, 1963 to August, 1964, 1 case was found to be bone tumor and 1 pyogenic arthritis as the result of pathological examinations after operation. These bacteriological studies were performed in the remaining 23 cases of tuberculous lesion of bone and joint. The results were as follows: (1) In direct smear, 4%(1 case in 23 cases) showed positive acid-fast bacilli. (2)In the culture of acid-fast bacilli on Ogawa media, 61%(14 cases in 23 cases) were positive. (3) By routine bacterial culture, mixed infections with staphylococci were found in 9% (2 cases in 23 cases). (4) In niacin test and peroxidase test, all of the 14 cases (or 61% of 23 cases) which showed positive for acid-fast bacilli in culture were positive. These indicated pathogenic and human type of acid-fast bacilli. (5) Sensitivity test to anti-tuberculous drugs on Ogawa media for the 14 cases revealed that was not resistant to isoniazid, PAS and streptomycin. (6)In catalase test, all of the 14 cases were positive.