Junior doctors face intense competition for specialist training posts this year, with 2.5 times mores applicants than jobs, the National Health Service said on Saturday.
NHS Employers, the body which represents health trusts in England, said there were 9,000 posts for an estimated 23,000 applicants.
Health chiefs said the battle for places means only the best candidates will be selected, but the Conservatives said it highlighted the need for more posts.
"It is a good thing for patients that there is competition for jobs," Sian Thomas, of NHS Employers, the body responsible for employment in the health service, told the BBC.
British-trained doctors face competition from overseas doctors working in the NHS after the appeal court rejected government attempts to give priority to UK graduates.
From Saturday, junior doctors will start to apply for the posts that allow them to train towards becoming a consultant or a family doctor.
Those who fail to win a place may seek a non-training job and reapply next year, look for work overseas or leave medicine.
Tory Shadow Health Secretary Andrew Lansley said: "Unless the government recognises the exceptional need for additional posts this year and in the next two years, we will see a new 'lost tribe' of doctors who fail to complete training."
The British Medical Association said it feared that the process could descend into a lottery.
"Trusts need to get their recruitment practices in order, and start preparing now to ensure that there is no unfairness, and no negative impact on patient care," said Ram Moorthy, who chairs its junior doctors' committee.
The BMA's chairman James Johnson quit last May after criticism from colleagues that he failed to convey doctors' anger over problems with last year's selection process.
