peer reviewed ; In Belgium, individual laboratory and treatment data of all HIV-infected patients seen in the 9 AIDS Reference Centres and 7 AIDS Reference Laboratories are collected prospectively since 2006. We present here an analysis of patients recorded in the cohort database between 1st of January 2006 and 31st of December 2008. During that period, 11982 patients were under medical follow-up in Belgium. Sixty-one percent of the patients were male and the median age was 39.8 at the time of first recorded viral load. Among the patients whose nationality or probable mode of transmission was recorded, nearly half (48.0%) were Belgian and 38.3% originated from Sub-Saharan Africa; heterosexual contacts were reported in the majority of cases (56.0%) followed by homosexual contacts (35.3%). A total of 145 deaths were reported. Around three quarters of the patients were on ART. The median CD4 cell count rose from 470 cells/mm3 in 2006 to 501 cells/mm3 in 2008. This cohort enabled us to obtain comprehensive information on the numbers and characteristics of HIV-infected patients currently being followed up in Belgium, and on trends in antiretroviral therapy and biological results. This will serve for planning purposes, evaluation of access to care and as a source of information for further studies.