To monitor the collective national impact of initiatives to expand the availability of HIV therapy including antiretroviral treatment (ART) countries need to monitor the proportion of HIV-infected individuals who are receiving HIV therapy, whether morbidity is decreasing, and HIV-infected individuals are experiencing increased survival, and if there is an overall decrease in the number of individuals dying of HIV. However, in many resource-constrained countries these data are limited or unavailable. Morbidity surveillance relies primarily on AIDS case reporting, but severe under-reporting limits the usefulness of these data. A variety of AIDS case definitions are in use and case definitions do not concur with clinical staging definitions. Harmonizing AIDS case definitions with clinical staging, providing resources and training to improve reporting, and using other surveillance systems, such as tuberculosis programme data to monitor morbidity are urgently needed. A cohort analysis of individuals in ART programmes to follow the progress and outcomes of these patients longitudinally is important to monitor quality of care and impact. Because the rapid scale-up of ART programmes may result in HIV drug resistance, surveillance for drug resistant viruses is also required. Very few resource-constrained countries have well-functioning vital registration systems to assess mortality trends and cause-specific mortality. Alternative approaches to measuring mortality trends, such as sample vital registration with verbal autopsy should be considered. Strong commitments from governments, international organizations and other partners are needed to establish and strengthen the HIV morbidity and mortality monitoring surveillance systems.