More than 12,000 NHS job posts have not been filled after people have retired, quit or moved on to other organisations, figures suggest.
Between May 2011 and May this year, there were 89,926 people who left the NHS in England but just 77,522 of the roles were filled, data from the Health and Social Care Information Centre shows.
The figures, based on NHS hospital and community health service staff, showed that the overall headcount of employees has reduced by almost 20,000 people since September 2009.
The number of people classed as "NHS infrastructure support" workers fell by about 20,000 from from 236,000 to 216,000 from 2009 to 2012. Managers and senior managers lost 5,000 and 2,000 positions respectively.
Health Minister Anne Milton said: "There are 2,400 more clinical staff working in the NHS than there were two years ago in May 2010, including over 3,700 more doctors, and over 900 extra midwives.
"In contrast, the number of admin staff has fallen by over 17,500, creating savings that will be reinvested into frontline patient care.
"Funding will increase by £12.5 billion over the next three years, protecting the NHS for the future."
The figures showed that qualified nursing, midwifery and health visiting staff posts have reduced by almost 5,000 in the last two years.
The Royal College of Nursing (RCN) said the reduction of posts would have an impact on patient care.
Dr Peter Carter, chief executive and general secretary of the RCN, said: "It simply isn't right to suggest that you can take these posts away without damaging patient care.
"Our members tell us every day about a health service which could easily buckle under the strain of delivering more care with fewer staff. Cutting staff is a short-sighted and ultimately futile way of attempting to save money, as patients can end up waiting longer and being more seriously ill by the time they are treated.
"Instead of cutting frontline staff, the NHS should pursue better planned, managed and designed services which keep people as well as possible and out of hospital. The RCN will continue to oppose job cuts locally and nationally on behalf of our members and the patients they care for."