Guidelines recommend antiretroviral treatment (ART) initiation at CD4 <350/µL for HIV-infected individuals in resource-limited settings. However, funding for treatment expansion remains uncertain. We forecast the mortality impact of ART expansion alternatives in Haiti. METHODS:: We used data from Haiti to develop a country-specific model of HIV disease. The model projects the mortality, total number of HIV-infected individuals, and number and coverage (% of those eligible) on ART by simulating cohorts of HIV-infected individuals over 10 years. We assessed 5 ART expansion scenarios, ranging from fully expanded ART (best case) to no new ART (worst case). RESULTS:: By 2010, the model predicts 103,500 individuals living with HIV in Haiti, of whom 27,300 were estimated to receive ART. Continuing ART initiation at current rates requires increasing the number on ART to 43,300 by 2020 (56% coverage), with 89,700 deaths estimated between 2010 and 2020. The number on ART could increase by 7,400 (+17.1%, best case) or decrease by 25,600 (-59.1%, worst case), resulting in 19,500 deaths averted and 9,900 fewer in care awaiting ART (best versus worst case). Results are sensitive to untreated disease progression and pre-ART loss from care. Increased HIV testing, linkage to care, and retention in care can avert additional deaths and achieve nearly 80% ART coverage with optimal policy improvements. CONCLUSIONS:: In resource-limited settings, continued improvements in HIV treatment access will save lives. Efforts to efficiently expand ART access should remain a global priority.