A total of 188 children and adolescents were examined. In all the children, blood Mycobacterium tuberculosis (MBT) DNA was determined by polymerase chain reaction (PCR) and MBT antigens (AG) and antibodies (AB) were by enzyme immunoassay. The studies have shown that it is expedient to concurrently determine MBT DNA and MBT AT in order to identify local forms of tuberculosis in children from risk groups. If the tests are positive, a comprehensive examination for tuberculosis is required; the presence of the syndrome of common disturbances is generally associated with tuberculous infection. When a local form of tuberculosis is excluded, preventive chemotherapy should be performed. Further negative tests for MBT DNA and lower MBT AT may be a criterion for the efficiency of preventive treatment. In children with tuberculosis, the results of repeated blood and urine tests for MBT DNA provide a way of evaluating the course of a tuberculous process and the efficiency of chemotherapy. PCR used to determine blood and urine MBT DNA is a highly specific test as positive results were in 79% of the children with tuberculosis.