It is widely acknowledged that the HIV and AIDS pandemic is a global emergency and that cheap, effective treatment should be provided for as many people as possible worldwide. But there are many challenges to rolling out antiretroviral (ARV) treatment in resource-poor settings. These include the cost of drugs (although these are falling rapidly), sustaining their supply and distribution, the complexity of treatment regimens, selection of patients for treatment, shortage of medical and nursing personnel, inadequacy of healthcare facilities, the need for uninterrupted, lifelong treatment, and monitoring for drug resistance. Great efforts, nationally and internationally, are required to meet these challenges.This work was supported in part by the University of Toronto and a grant from the United States National Institutes of Health's Fogarty International Center to the University of Cape Town's capacity-building program in International Research Ethics in southern Africa (Program Director S. R. Benatar).