Campaigners angry about the “creeping privatisation” of the NHS took part in a demonstration to raise awareness of their concerns.
Members of the local Defend the NHS pressure group spent two hours outside the Specsavers shop in North Street, Brighton, on Saturday.
Specsavers was awarded the contract to provide NHS hearing aid services earlier this year.
The service was previously run by Brighton and Sussex University Hospitals NHS Trust.
Campaigners fear the move is only the beginning of a slippery slope and NHS trusts across the country will increasingly lose other services to private companies.
It follows the controversial sweeping changes to the NHS that have made it easier for private firms to apply for NHS contracts.
A spokesman for the group said: “A lot of people were very surprised when we explained what was happening."