This background paper aims to increase understanding of the requirements for introducing and scaling up provision of antitetroviral therapy (ART) as part of comprehensive HIV/AIDS programmes in resource-poor countries. The paper provides an overview of experience and lessons learned with regard to the feasibility of ART in resource-poor settings, the different approaches being taken to delivery of ART, and the issues to be considered in scaling up ART provision. The review is based on published and unpublished literature, interviews with key informants, web searches and country information