Some 75,000 NHS employees were attacked last year, at a cost to the health service of more than £100 million.
A BBC Panorama investigation found that violence against NHS staff continues, despite the government launching a zero tolerance policy on attacks against staff.
The total cost to the NHS is equivalent to the salaries of 4,500 nurses, the programme calculated, when factors such as absenteeism, extra training and security and legal bills are taken into account.
Moreover, Panorama found that less than two per cent of all attacks resulted in prosecutions.
However, NHS Security Management Service (SMS), the body responsible for providing security within the health service, claims that successful prosecutions in England have increased 16-fold, while other measures are also acting to increase employee safety.
Specialist training is offered to help staff prevent and counter abuse and so far 250,000 employees have benefited. Last week, NHS SMS reported that nine in ten staff trained in conflict resolution can manage verbally abusive patients, up from six in ten before training.
An NHS SMS spokesman said: "Violence against NHS staff is completely unacceptable. No NHS staff member should go to work thinking that violence or abuse is part of their everyday life.
"There is still a considerable amount of work to do but we feel the improvements that have been made show that the NHS is making headway against the antisocial minority who think it is acceptable to assault and abuse the staff who are the lifeblood of the NHS."
The Conservatives commented that it is "disgraceful" for thousands of NHS staff to risk attack while working for the public benefit.
Shadow health secretary Andrew Lansley argued: "We must have a tougher system in place to protect staff. We have already argued in parliament for stronger legal protection of NHS employees.
"It is vital a clear message is sent out to the public that people who attack NHS staff will face severe punishment."
The Liberal Democrats also urged for more action, calling on the government to "crack down" on violence in hospitals.
Lib Dem health spokesman Norman Lamb agreed that proper staff training is essential but voiced concern that budget cutbacks, caused by deficits, is "putting already over-burdened staff at serious risk."
Mr Lamb also queried whether enough cases are leading to criminal prosecution, urging police to take the matter seriously and maintain a "robust approach" to violence against NHS staff.
He concluded: "Everyone entering a hospital must be 100 per cent clear that violence against staff is never acceptable."