Attacks on NHS staff fell last year, but only a small proportion were investigated by the police, new figures show.
Health minister Ann Keen said there were 55,709 assaults in 2006-07, 2,986 fewer than the year before, and 4,676 fewer than in 2004-05.
But despite the NHS Counter Fraud and Security Management Service having a policy of prosecuting cases not pursued by the police or Crown Prosecution Service, only 869 people were investigated by officers.
Despite the total drop in attacks, there were still 41,569 assaults on mental health and learning disabilities workers during the past year, a rise of 224 on the previous year.
Ms Keen said: "It is encouraging that violence against NHS staff has actually fallen for two years running.
"This shows that the approach we have taken is beginning to deal with the antisocial minority who assault and abuse NHS staff.
"But the number of assaults is unacceptably high and there is still a great deal of work to do to tackle those responsible."
Dermid McCausland, managing director of the NHS Counter Fraud and Security Management Service, added: "NHS staff deserve to work in an environment where they are safe from violence and abuse from the people they are trying to help."