The Health Secretary says this action will cause discomfort, uncertainty and difficulty.
I'm at Peterborough City Hospital to find out first hand what the impact is.
Around 80 non-urgent clinic appointments were cancelled ahead of the strike. Only two operations have been postponed.
Around a third of doctors are not members of the BMA and of those that are, 21% of GPs and 15% of hospital consultants voted against industrial action.
Just 8% of doctors working in the NHS in England went on strike, according to the Government. More than 20,000 patients were affected.
Doctors are taking industrial action for the first time in almost 40 years but what are the arguments for and against pension reforms?
More than half of people surveyed in an exclusive ITV News poll oppose the doctors' strike over pensions that will take place on Thursday.