The University of KwaZulu-Natal - Centre for the AIDS Programme of Research in South Africa (CAPRISA) HIV/AIDS Clinical Trials Unit (CTU) brings together three senior investigators from the leadership of the HPTN, MTN and IMPAACT to lead a uniquely South African CTU, comprising a consortium of five partner institutions conducting research in five research priority areas. To achieve this, the CTU includes six well-established clinical trials sites which have a track record for being able to recruit and retain large cohorts for prevention and treatment trials. The rural community based CAPRISA Vulindlela Site, with HIV prevalence of 42.7% and incidence of 8.5 per 100 person-years in cohorts of adolescent and young women (annual retention rate: 95.0%) will conduct vaccine, microbicide and prevention trials. The Aurum - CAPRISA Site, which serves gold miners and their communities, has HIV prevalence of 32.1% and HIV incidence of 4.1 per 100 person-years in gold miners (annual retention rate: 95.1%) will conduct vaccine and clinical management optimization trials. The CAPRISA - Thekwini Site at one the country's largest TB clinics, which treated 8580 new TB patients last year with HIV prevalence of 64.6% and ART adherence of 95.2%, will conduct optimization of clinical management trials. The Umbilo Site at the Doris Duke Medical Research Institute in Durban, which is well suited to conduct clinically intensive phase I trials, also has a sex worker cohort with 57.9% HIV prevalence and an incidence rate of 9.8 per 100 women-years (annual retention rate: 98%) for vaccine and microbicide trials. The Umlazi Site at a 1,200 bed Durban hospital manages about 12,000 deliveries annually with HIV prevalence of 50.7% and MTCT rate of 20% at 9 months and the Cato Manor Site at a Durban primary health clinic, manages 1320 pregnancies annually with HIV prevalence of 48.1% and MTCT rate of 18% at 9 months will both conduct pMTCT trials. The CTU administrative component has eleven cores of expertise (pharmacy, data management, statistics, laboratory, behavioral, health economics, bioethics, community involvement, quality assurance, regulatory and training) which will support site level activities and centralize certain functions, where appropriate. An experienced full-time Operations Director will coordinate support provided by the cores to each site and will ensure effective systems for monitoring the quality of trial implementation at each site. Effective communication between sites and the CTU administrative component and collective monitoring of CTU performance occurs through the monthly meetings of the CTU Executive Committee comprising the PI, co-PIs, Operations Director, Administrative Manager and the Site Leaders. Further, each site has a community advisory committee with representatives on the CTU Community Advisory Board. This CTU encompasses a track record of scientific leadership in HIVNET, HPTN, HVTN, and CIPRA, ready access to large cohorts at high HIV risk, established clinical trial infrastructure with experienced personnel in the cores and sites, a training programme integrated with Fogarty AIDS training, and potential scientific contributions well aligned with the scientific agendas of five Networks.