Tuberculosis is an infectious disease caused by tuberculosis bacilli (bacteria from the Mycobacterium tuberculosis species). The disease most commonly affects the lungs, but in a third of patients, other organs are also affected (joints, brain, liver, lymph nodes). The source of infection for a child is an adult patient or occasionally an adolescent, who coughs and excretes bacilli. Young children are usually not contagious. The infection does not always mean active disease. Several types of tuberculosis are recognised. Tuberculosis is often silent in young children, but adolescents and adults usually have typical clinical signs such as prolonged fever, cough, malaise, loss of appetite, night sweats and weight loss. The diagnosis is based on the history, clinical signs and examination, tuberculin skin testing (and interferon-gamma release assays, if available), chest x-ray and microbiological confirmation. Early detection and treatment of tuberculosis in adolescents are very important to prevent transmission to other persons. Tuberculosis is an infectious disease that must be reported. In this article, we present the case of an adolescent with suspected post-primary tuberculosis.