Tuberculosis in childhood is an important cause of mortality worldwide. The disease is difficult to diagnose and the underlying immune mechanisms are poorly understood. Advances in the application of molecular genetic tools, as illustrated by the recent completion of the genome sequence of Mycobacterium tuberculosis, provide opportunities for the development of improved diagnostic tools and vaccines for tuberculosis. It is important that research efforts in this area should include consideration of the unique problems and possibilities related to the control of tuberculosis in children.