Tuberculosis is still a significant clinical problem. Rate of incidence of the disease in the paediatric population is a good measure of the epidemiological situation in the area. Tuberculosis in children, always primary, is significantly different in its course from tuberculosis in adults. The most common form in children is a disease of the lung parenchyma and the clinical course may be atypical, crafty, oligosymptomatic and carried out under the guise of clinical other diseases. The diagnosis of tuberculosis in children is based on carefully collected history, clinical examination and the results of additional tests (tuberculin skin test, chest X-ray and sputum smear microscopy). Microbiological test result is the gold standard. Gastric lavage were collected to study in young children, in older – induced sputum concentrated solution of NaCl or bronchial lavage obtained during bronchoscopy. The only available vaccine against tuberculosis is BCG. In Poland, the vaccination is carried out in the first 24 hours of life for all neonates who do not have contraindications. The BCG vaccine does not protect against the disease, but only reduces the number of severe forms of tuberculosis in children. Treatment options include combination regimens consisting of two phases: a phase of intensive treatment of sterilization and a continuation phase. The article presents a case study of 14-year-old girl hospitalized in the Department of Paediatrics, Paediatric Nephrology and Allergology, because of lack of improvement in outpatient treatment of pneumonia. Due to the absence of regression of inflammatory changes on the chest radiographs and persistent auscultatory changes of the lung fields, a series of tests was performed, finally recognizing tuberculosis.