Many patients clinically ask, “Does a positive tuberculin test mean that I have tuberculosis?” Not necessarily. A positive tuberculin test can mean different things to different people. In infants and young children, a positive tuberculin test often means that they have been infected with the tuberculosis bacterium and have developed antibodies that do not require BCG vaccination. Generally, a tuberculin test should be done after 3 months of BCG vaccination to see if the body has developed immunity to BCG. If the tuberculin test is positive, the BCG vaccination is successful; otherwise, the BCG vaccination should be repeated. In adults, a positive tuberculin test indicates that they have been infected with tuberculosis but are not necessarily ill now. When the tuberculin test is strongly positive, it indicates active tuberculosis in both infants and adults, and prompt testing for tuberculosis, imaging, and blood sedimentation should be performed to determine the diagnosis and treatment.