In general terms, the objective of the EuroSIDA study is to continue a long-term, prospective collection of clinical, laboratory and therapeutic data as well as plasma on a large cohort of consecutive HIV infected patients from across Europe in order to (1) assess the factors associated with the clinical, immunological and virological course of HIV infection and HIV-related co-infections and co-morbidities, and (2) continue to provide and develop a surveillance system to describe temporal changes and regional differences in the clinical course of HIV and HIV-related co-infections and co-morbidities in Europe.