Objective: The “AIDS epidemic update” (2007) published by the United Nations (UN) and World Health Organization (WHO), reports lower estimates of incidences of persons infected with HIV globally. This study evaluates the cost savings of these lower estimates on costs associated with patients being treated by antiretroviral (ARV) drugs and opportunistic infection (OI) prophylaxis. Methods: Estimated differences in incidences of persons infected with HIV for the eight global regions in years 2006 and 2007 were calculated from UN reports. This difference was then multiplied by the average percentage of patients on ARV and OI treatment. Further, to derive the total cost savings associated with the ARV cohort, the number of patients on ARV medication was multiplied by a weighted average of first and second line ARV drug costs, lab costs, counseling costs, inpatient costs and outpatient costs, for each region. Conversely, only counseling and OI drug costs were included in the total cost of patients receiving OI prophylaxis treatment, for each region. Costs were reported in 2006 US dollars. Sensitivity analysis performed on all key parameters. Results: The reduction of incidences of persons infected with HIV from 2006 to 2007 resulted in a total cost savings of $309.5 million, or 42%. Separately, the patients being treated by ARV drugs attributed a cost savings of $274.7 million, contrary to patients on OI drugs attributing $34.8 million to cost savings. The greatest savings were shown in the Sub-Saharan Africa region ($191.1 million). Conclusion: Based on the revised estimates, the worldwide savings is a large percentage of the treatment budget. Notwithstanding increased incidence rates in subsequent years, these savings should continue beyond 2007.