Junior hospital doctors in England began a five-day strike on Thursday, a week before a general election in which the state of the publicly funded National Health Service is a major issue.
It follows nearly a dozen similar protests by doctors below specialist, consultant level over the last 18 months.
The NHS is grappling with a massive backlog caused by the Covid-19 pandemic.
A recent survey suggested that less than a quarter of Britons were satisfied with the NHS, an unprecedented level.
As well as delays to operations and starting cancer treatment, the public also face long waits to see a doctor at their local surgery.
The doctors have been asking for 35-percent "pay restoration" as a starting position amid a cost-of-living crisis.
They have said they will call off the action if Conservative Prime Minister Rishi Sunak comes to the table with a credible commitment to increase their pay.
Shivram Sharma, a junior doctor working in London, told AFP he and his peers were protesting "because we've been in dispute with the government for 20 months... and we're yet to be provided a credible offer".
He added: "Doctors are tired. We're frustrated but we're ultimately scared... We've seen the quality of care in this country decline."
Sharma said patients were being short-changed and having to endure longer waiting times for treatment, particularly in accident and emergency, and doctors were leaving the profession.
"We need to keep doctors here and stop them from leaving because of the poor conditions and poor pay," he said on a picket line out Saint Thomas' Hospital in central London.
"Until we deal with that, the waiting list will continue to go up (and) wards will continue to remain understaffed."
Central to the junior doctors' demands is to increase pay from GBP15 (just under $19) an hour to GBP20.
The deputy chair of the British Medical Association's Junior Doctor Committee, Sumi Manirajan, said wages had not kept up with inflation over the last 15 years and doctors have to pay thousands out of pocket for indemnity fees, courses and exams.
Manirajan said the government was already making a number of public spending commitments for the general election on July 4.
"Rishi Sunak has made a commitment to spend GBP2.5 billion on a national (military or civic) service. It would cost GBP1 billion to pay the doctors," she said.
The government had already "wasted three billion pounds fighting us", she added.
"So the money is there. It's a political choice on where they spend it."
The strike runs until Tuesday, two days before a general election which the main opposition Labour party is expected to win.
Labour's health spokesman, Wes Streeting, has said any Labour government would not meet the 35-percent demand but that there is "space for a discussion".
Decades-high inflation in 2023 saw workers from sectors across the economy, from teachers to train drivers, stage walkouts.
Sunak's government has said the doctors' demands are unaffordable because of stretched public finances.
It has accused the strike organisers of being politically motivated.
