Doctors going on strike again over pay is "inflicting pain and misery" on patients, says Health Secretary Wes Streeting.
"We could do without this reckless action," he said, adding it could harm patients.
The five-day walkout in England by resident doctors, the new name for junior doctors, runs until 07:00 GMT on Wednesday.
The doctors' union - the British Medical Association (BMA) - says they are still not paid enough and there are too few training places or jobs.
The NHS says nearly all services will keep running, and patients should attend appointments unless advised otherwise. Hospitals will come under the most strain - resident doctors make up about half their medical workforce.

