Figures from the NHS Information Centre show there has been a rise in the number of long-term vacancies in most areas of the NHS for the first time in five years.
According to the data, one in five empty posts remain unfilled for three months or more, and total vacancy rates have risen in most areas.
Researchers found that the number of empty vacancies for hospital doctors and dentists, excluding trainees, rose from 3.6% of the total number of jobs last year to 5.2%.
The number of long-term vacancies also rose from 0.9% to 1.5%.
However, in the nursing sector total empty vacancies rose from 2.5% to 3.1%, with long-term vacancies up from 0.5% to 0.7%, but this was higher in London going from 1.2% to 1.6%.
Bucking the trend, the number of empty jobs for psychiatric nurses fell but long-term vacancies rose from 0.6% to 0.9%.
Speaking about the data, Dr Peter Carter, chief executive of the Royal College of Nursing (RCN), said: "While we are concerned about long-term vacancies, even unfilled short-term vacancies leave nurses under unsustainable pressure and, with higher workloads, too busy to provide the standard of care they would like."