Three countries in Southern Africa have the highest adult HIV prevalence in the world: Swaziland (25.9%), Botswana (24.8%), and Lesotho (23.6%). Fiscal policy is crucial for addressing this HIV/AIDS crisis. Utilizing a calibrated model, this paper investigates the impact of fiscal policy on reducing the HIV/AIDS incidence rates in these countries. In particular, we studied the welfare impact of different taxation and debt paths in these countries in reducing the HIV/AIDS prevalence rates. This is particularly important given the current concerns about dwindling foreign aid (especially the global AIDS fund), and the fiscal deterioration and sustainability in these countries.