In this study, 151 school children and students with tuberculosis registered in Aichi Prefecture during 1983 to 1987 were investigated. The results were as follows: 1) The extent of lesions were not so advanced, as shown by the fact that 27.2% were cavitary and 31.8% were bacteriologically confirmed. 2) They were detected mainly by symptomatic visit to physicians (39.1%), periodic mass radiography (31.8%) and contacts survey (20.6%). The proportion of the former symptomatic visit was comparatively lower than in other age groups. 3) Patient's delay in cases detected by symptomatic visit was not so evident, however, there is a certain grade of doctor's delay; for instance, 22.0% of them took 2 months and more to be diagnosed. 4) 77.5% of them were vaccinated with BCG once or more, in most cases more than 5 years before their detection. 5) Sources of infection were specified in 52.3% of the cases. Most of them were found in their household and were bacteriologically confirmed at the time of detection. In some students their classmates were suspected as their possible source of infections.