PIP: The situations when prophylactic antibiotics should be given to children in developing countries where BCG vaccination is common are explained. In most countries, 80-90% of children have been vaccinated with BCG by the age of 1. Since BCG makes a tuberculin (PPD) test moot, because all BCG-vaccinated persons have positive PPD tests, the only children in developing countries who can be diagnoses with TB are those who are vaccinated and live in close contact with a TB infected person. The only prophylactic medication recommended for children is daily isoniazid, 5 mg/kg for 6 months. Preventive medication is never given to healthy BCG-vaccinated children. The multi-drug regimen is not appropriate because young children have relatively few Mycobacterium bacilli, and developing countries cannot even afford to treat infected adults with these regimens. The only situations for treating children prophylactically are: 1) healthy children, under 5, not BCG vaccinated, and tuberculin positive; 2) healthy children, age 5-14, tuberculin positive with documented negative PPD test within 2 years, and 3) age 1, not BCG vaccinated, recently diagnosed as tuberculin positive. In an infant living in close contact with an infected source, a PPD test is done after 3 months of treatment with isoniazid, and if positive, treatment is continued for another 3 months. If the PPD test is still negative, the BCG vaccination is given.