Background. The rapid scale-up of antiretroviral therapy in resource-limited settings has greatly increased demand for antiretroviral medicines and raised the importance of good forward planning, especially in the context of the new 2010 WHO treatment guidelines. Methods. Forecasting of the number of people receiving antiretroviral therapy from 2010 to 2012 was produced using three approaches: linear projection, country-set targets, and a restricted scenario. Two additional scenarios were then used to project the demand for various antiretroviral medicines under a fast and slower phase-out of stavudine. Results. We projected that between 7.1 million and 8.4 million people would be receiving ART by the end of 2012. Of these, 6.6% will be on second-line therapy. High variation in forecast includes reductions in the demand for d4T and d4T increases in the demand for tenofovir, emtricitabine followed by efavirenz, ritonavir, zidovudine and lopinavir; lamivudine, atazanavir, and nevirapine. Conclusion. Despite the global economic crisis and in response to the revised treatment guidelines, our model forecasts an increasing and shifting demand for antiretrovirals in resource-limited settings not only to provide treatment to new patients, but also to those switching to less toxic regimens.