The increased risk of developing tuberculosis (TB) among those infected with HIV has prompted a need to reconsider the institution of preventive therapy/chemoprophylaxis with one or more antituberculosis drugs. Prior to the initiation of preventive therapy for tuberculosis, it is essential to rule out active TB. The target population for chemoprophylaxis among HIV seropositives includes all Mantoux (PPD) positive individuals who do not have active tuberculosis and could include all PPD negative individuals living in high prevalence region for TB. The optimal duration of preventive therapy with single drug isoniazid, daily or twice weekly, should be greater than six months to provide the maximum degree of protection against tuberculosis. The effectiveness of preventive therapy should be evaluated at regular intervals by monitoring patients for drug adherence, drug toxicity and for the development of tuberculosis. Though the impact of preventive therapy on an individual basis may be rather small, widespread implementation would have substantial impact on morbidity due to tuberculosis and some impact on mortality. Till the vast majority of HIV positive individuals in the world can access antiretroviral therapy, preventive therapy for tuberculosis should be offered at voluntary counselling and testing centres, as part of a package of care that includes prophylaxis and treatment of opportunistic infections, nutritional support and counselling.