TB notification rate in infants and children 0-4 years was 24.3/100,000 in Argentina, in 2000, for a global incidence of 31.8/100,000. A 17% of all TB cases occurred in children (0-14 years), indicating a very active TB transmission. Usually TB is diagnosed when the disease is already advanced. Main criteria for the diagnosis are: a previous contact with an infectious TB patient, a positive PPD test result and clinical--radiological signs and symptoms. Bacteriology plays a limited role in diagnosis; gastric aspirate is the most often used specimen for bacteriological examination in children. Culture is performed on solid egg-media, but other more recently developed culture media systems are available in reference laboratories. Nucleic acid amplification assays are also used, but its systematic quality control is still lacking. Their results should be considered only as complementary. Strengthening of the laboratory network will contribute to increase diagnostic certainty of childhood TB, to improve reliability of cases reported, and to a better knowledge of the drug resistance profile. Early diagnosis of TB in children, by contacts investigation of infectious patients, followed by preventive chemotherapy or treatment when necessary, may revert the current epidemiological situation. TB meningitis in the 0-4 years group showed a significantly more pronounced decline than that of adults TB for the period 1980-2000, (only 10 meningitis cases were diagnosed in year 2000, 0.29/100,000), confirming the protection conferred by BCG vaccination when applied to newborns with a continuously high coverage.