This report has grown out of the implementation of an Integrated Bio Behavioral Surveillance (IBBS) study among most at-risk populations in Lebanon. AIDS-related policies and programs in the Middle East and North Africa region are highly constrained by the lack of accurate information about the full scale of the epidemic. This is for a number of reasons, including limitations of existing surveillance, and intense stigma associated with the disease. Lebanon urgently requires greater understanding of its epidemic and high quality integrated bio-behavioral surveys of vulnerable populations are a prerequisite for greater understanding of low prevalence epidemics, such as Lebanon's. The costs of continuing to respond without adequate data or insight greatly outweigh the cost and complexities of such a survey. A Lebanese survey will also contribute to a greater regional understanding of the magnitude and dynamics of the Middle East's epidemics. The study aims to provide an estimate of HIV prevalence among four major vulnerable groups in Lebanon, namely men who have sex with men (MSM), prisoners, commercial sex workers (FSWs) and intravenous drug users (IDUs); provide an estimate of co-infection with Hepatitis B and C among HIV positive participants in the MSM population, FSW population, IVUDs, and the prisoners; provide an estimate of level of infection of Hepatitis C among the entire intravenous drug user population; foster research collaboration for the project between NGOs involved with the vulnerable groups, the National AIDS Program and the American University of Beirut and contribute to building the research capacity of the NGOs involved; estimate the population size of the four vulnerable groups using the multiplier method based on NGO sources and estimates; and gain greater insight into major HIV transmission dynamics among the four vulnerable groups in Lebanon.