A tuberculosis epidemic occurred in a class at a technical center in a large furniture company. An index case was a male student who had a severe family history of tuberculosis and his sputumsmear was Guffky 3. PPD skin test and routine chest X-ray examination were immediately done on the forty-two classmates. As the result of these examinations, the distribution of maximum diameter of erythema in PPD skin test showed bimodal distribution, and tuberculosis was discovered in five patients by chest X-ray examination.During follow up for eighteen months another three new patients were found. In this company, routine chest X-ray examination had been carried out. The patient's delay and insufficient ventilation in the dormitory were considered to be the main causes of the tuberculosis epidemic.
