The NHS in England has announced it will finally give people a drug to dramatically reduce the risk of being infected with HIV, from next month.
The health service had previously fought against paying for Prep and even took the issue to court, unsuccessfully, last year.
The drug will be given to 10,000 people in a £10m trial lasting three years.
The Terrence Higgins Trust said it was "crucial" the NHS delivered plans to offer the protection routinely.
Prep (pre-exposure prophylaxis) is a daily pill that disables HIV before it gets a stranglehold in the body.
Trials suggest it can cut the risk of being infected by up to 86%.
People buying the drug privately has been linked to the first fall in new infections in gay men.
Sexual health clinics in London, Brighton, Manchester, Liverpool and Sheffield are expected to be the first to offer Prep to high-risk people, starting September.
Prep: HIV By James Gallagher Health and science reporter, BBC News website