Three-quarters of claimants who apply for sickness benefit are found fit to work or drop their claims before they are completed, according to official figures.
Over a 22-month period, 887,300 of the 1,175,700 applicants for employment and support allowance (ESA) - the successor to to the old incapacity benefit - failed to qualify for any assistance.
Of those 458,500 - 39% - were judged fit to work while a further 428,800 - 36% - abandoned their claim before their medical assessment had been completed, according to the figures released by the Department for Work and Pensions.
Employment Minister Chris Grayling said they underlined the need to reassess people still on the old incapacity benefit - a process which the Government began rolling out last month.
"Once again we have clear evidence of the need for change in our welfare system," Mr Grayling said.
"We now know very clearly that the vast majority of new claimants for sickness benefits are in fact able to return to work. That's why we are turning our attention to existing claimants, who were simply abandoned on benefits.
"That's why we are reassessing all of those claimants, and launching the work programme to provide specialist back to work support.
"We will, of course, carry on providing unconditional support to those who cannot work, but for those who can it's right and proper that they start back on the road to employment."
The DWP figures cover the period from October 27 2008, when ESA was introduced by the former Labour government, to August 31 2010.
