Thousands of junior doctors marched on Downing Street on Monday night in protest against the government's new proposed contract, which would see young medics work longer hours and take a significant pay cut.
It is estimated that about 5,000 junior doctors protested outside Westminster Hall this evening, just hours after a meeting with NHS chiefs was cancelled.
The British Medical Association warned last week that there could be a mass exodus of junior doctors if the government imposes the new contract.
Thousands of people joined in the protest, with many holding banners with slogans on such as "save our contracts, save our patients, save our NHS", "not safe, not fair" and "hands off our pay".
There were also reports of demonstrators chanting "save our NHS".
The contract would alter junior doctors' normal working week, so they could work Saturdays and up to 10pm every night of the week except Sunday.
This would mean that junior medics would be paid a standard rate working those hours, losing out on money.
The new contract is due to come into effect next August and there has been as sharp increase in the number of doctors applying for documents to work abroad, leading to fears that there could be an "exodus" of medically trained staff.