The UK CHIC Study is a collaboration that started in 2001 to put together data relating to clinical care and treatment of HIV. The study database contains routinely collected clinical information on HIV positive individuals aged over 16 years who have attended one of the collaborating centres for care at any time in 1996 or thereafter. Currently, the database contains more than 45,000 records of patients who have attended for care at one of a number of HIV clinics around the UK. The purpose of the study is to analyse the data to monitor the uptake and response to therapy among individuals with HIV in the UK. Other research themes include: HIV and pregnancy; HIV and hepatitis co-infection; and HIV and ageing.