Junior doctors in England are to stage more strikes, in December and January, after rejecting a new pay offer put forward in talks with government.
The British Medical Association (BMA) union said the proposal was worth an extra 3% on average this year. This is on top of an 8.8% rise already given.
The strikes will be for three days from 07:00 on 20 December and six days from 07:00 on 3 January.
The new-year walkout will be the longest in the NHS's history.
It coincides with what is traditionally one of the NHS's busiest periods, with emergency services often under huge strain.
The breakdown in talks comes after five weeks of negotiations during which industrial action had been suspended.
The BMA wants a 35% pay uplift, to make up for what it says have been below-inflation rises since 2008.
The government refused to comment on the detail of the offer, with sources saying there had still been room for movement if the talks had continued.
Health Secretary Victoria Atkins said it was "disappointing" junior doctor leaders had walked away from negotiations.
"The new strikes will result in more disruption for patients and extra pressure on NHS services and staff as we enter a busy winter period, risking patient safety," she added.
Dr Robert Laurenson and Dr Vivek Trivedi, who co-chair the BMA junior doctors committee, said: "We have been clear from the outset of these talks that we needed to move at pace - and if we did not have a credible offer, we would be forced to call strikes.
"After five weeks of intense talks, the government was unable to present a credible offer on pay by the deadline.
"Instead, we were offered an additional 3%, unevenly spread across doctors' grades, which would still amount to pay cuts for many doctors this year."
Sir Julian Hartley, of NHS Providers, which represents health managers, said: "This is the outcome that NHS leaders were dreading."
Since industrial action started in the NHS, more than a million appointments and treatments have had to be cancelled.
There have been walkouts by nurses, ambulance workers and physiotherapists, among others, but those by doctors have been the most disruptive.
Pay deal
The rise given to junior doctors in April was weighted so those at the start of training - and therefore earning the least money - received the biggest rises.
The BMA's announcement of more strikes comes after the union reached a pay deal last week with the government on senior doctors, or consultants, who have also been taking strike action.
Consultants will now vote on that deal, which involves an average pay rise of nearly 5% in January on top of the 6% rise they received in April.
Other health workers, including nurses, accepted a pay offer of an extra 5% and a one-off sum of at least £1,655, in May.
