Abstract: The tuberculin test has been the traditional method for detecting infection with tubercle bacilli. Epidemiologists have used it extensively for assessment of the tuberculosis situation in different communities. In clinical practice, it is used to find out the presence or absence of tuberculous infection. This aids in the differential diagnosis of tuberculosis among children and to decide about the administration of chemoprophylaxis. The tuberculin skin test is one of the few investigations dating from the 19th century that is still widely used. It was developed by Koch in 1890, but the intradermal technique currently in use was described by Mantoux in 1912. After such a long history it is surprising that the interpretation of the test remains controversial. The most widely used tuberculin is purified protein derivative (PPD), which is derived from the cultures of Mycobacterium tuberculosis. Although the tuberculin test is widely used for detection of tuberculous infection among children, there is no clear understanding about its performance and interpretation. This article has been written with the aim of elucidating the performance and interpretation of the standard tuberculin test.