NHS workers, campaigners and union representatives are marching in London to protest "yet more austerity" to the health service.
The protest, called #ourNHS, is marching against plans which could see hospital services in nearly two-thirds of England cut back.
It says pay restraints for NHS staff has led to 25,000 nursing vacancies.
Labour leader Jeremy Corbyn is expected to address protestors at the march, once it gets to Parliament Square.
The march began outside private healthcare company Virgin Care in Tavistock Square, and will end with a series of speeches in Westminster.