HIV/AIDS has dramatically increased the incidence of tuberculosis (TB) in sub-Saharan Africa where up to 60% of TB patients are co-infected with HIV and each year 200,000 TB deaths are attributable to HIV co-infection. Now HIV threatens TB control in Asia, Eastern Europe and Latin America. Antiretroviral (ARV) drugs can prevent TB by preserving immunity but cohort analysis shows that early therapy, plus high levels of coverage and compliance, will be needed to avert a significant fraction of TB cases. However, ARVs could enhance the treatment of TB while TB programmes provide an important entry point for the treatment of HIV/AIDS.