Diagnosis of tuberculosis in children is usually based on clinical signs and symptoms, chest roentgenogram, tuberculin testing and history of contact with adult patients. The diagnostic tests for tuberculosis can be broadly divided into 2 groups: demonstration/isolation of Mycobacterium tuberculosis or one of its components [Ziehl Neelson (ZN) staining, special stains, cultures, polymerase chain reaction]; demonstration of host's response to exposure to M. tuberculosis (Mantoux test, serodiagnosis). The yield of tests used for demonstration of mycobacterium or its components is poor because of pauci-bacillary nature of disease in children. Diagnostic use of PCR is still experimental. Serodiagnosis does not have acceptable sensitivity and specificity hence, at present, does not have any role in diagnosis of tuberculosis in children. The diagnosis is suspected on history and a combination of imaging studies and Mantoux test still remains the most widely used investigation.