The first 48-hour walkout began at 8am on Wednesday with tens of thousands of doctors expected to join the action. Juniors in urgent and emergency roles are not joining the strike.
NHS England said that over 5,000 procedures had been cancelled ahead of the strike.
A MORI opinion poll for the BBC found that 65% of the public supported the junior doctors going on strike, with 17% against, down from 22% at last month's 24-hour strike. The majority of the public, 57%, blamed the government for the dispute.
Junior doctor strike
In a video message to members junior doctors committee chairman Dr Johann Malawana said it was ‘extraordinary’ that the government remained ‘unwilling to put a brake on the imposition’ as doctors prepared for the two-day action.
‘What kind of way is this to treat a profession?' said the strike leader. ‘To dictate, not listen. To bully, not negotiate. To shatter morale through a concerted anti-doctor campaign.’
Dr Malawana said he wanted to assure junior doctors of his committee's ‘determination to resist the imposition’.
‘My resolve and that of the junior doctors committee in this matter is clear,’ he said.
‘Our goal is to prevent imposition of this contract and instead achieve through negotiation a contract that addresses our outstanding concerns.’
‘Let us show the government over the next couple of days that our determination and resolve are unwavering.’
He added: ‘We won't be bullied, attacked and made the scapegoats for a government flying blind.’
Last week health secretary Jeremy Hunt defended the imposition as the right thing to do to show the government would not be held to ransom by any group of staff.
Speaking to NHS leaders at the Nuffield Trust's policy conference, Mr Hunt said it would have been the ‘wrong thing to do’ to step back from imposing a contract which the BMA says is unsafe for patients and unfair for doctors.
Hunt rejects strike
Mr Hunt defended the imposed contract recommended by lead negotiator Sir David Dalton as a ‘mid point’ between the government and BMA’s positions, and said it would have been ‘a backward step’ not to accept it.
It would have 'sent a signal' to the rest of the NHS that one group is able to hold the government and patients 'to ransom' with 'completely unreasonable behaviour’, said Mr Hunt.
In a statement published as the strikes began, a DH spokeswoman said: 'Patients have so far seen more than 19,000 operations cancelled as a result of the BMA's irresponsible and unjustified industrial action.
'The new contract, 90% of which was agreed with the BMA, and endorsed by senior NHS leaders, is a very good deal for doctors and the NHS. It will mean an average 13.5% basic pay rise with a cap on the number of long shifts worked to improve safety. We urge junior doctors to look at the detail of the contract and the clear benefits it brings.'