Two students of different high-schools were found to have pulmonary tuberculosis by school medical examination. These two students learned in the same private extra-school tutoring institute when they were junior high-school students. Assuming this event as a group infection of tuberculosis in the extra-school tutoring institute, we performed an extraordinary examination on the teachers working there. 2) In the extraordinary examination, a patient who could be judged as the source of infection was found. 3) As a result of extraordinary examination on students learning in the institute, a bimodal distribution was noted in the size of tuberculin test, compared with the results of tuberculin test at the first grade of junior high-school, the reaction was amplified. Twenty four students were subjected to chemoprophylaxis. 4) One case of pleurisy occurred from a student recommended chemoprophylaxis by the ad hoc committee on epidemic of tuberculosis, and the recommendation was neglected by an attending physician.
