A positive tuberculin test indicates that the body is infected with Mycobacterium tuberculosis or has been vaccinated with BCG. In a country with a high epidemic rate like ours, where the rate of Mycobacterium tuberculosis infection is high and most people have received BCG vaccination, a positive test cannot be diagnosed as tuberculosis. Only moderately positive or strongly positive BCG tuberculin tests in children under 3 years of age who have not received BCG vaccination indicate the possibility of active TB in the body. It should be noted that many people clinically have a strong positive tuberculin test years after they have been cured of tuberculosis, and this may be true even in the case of lung cancer. Therefore, the tuberculin test results need to be judged and interpreted in conjunction with the rest of the patient’s clinical picture to avoid delaying the diagnosis of other, more important diseases.