Three out of four people applying for sickness benefits are being found fit to work or are abandoning their claims, according to Government figures.
Of the 686,500 applicants assessed for the Employment and Support Allowance (ESA) between October 2008 and November 2009, 39% were judged able to work, while 37% stopped their claims before their assessments were completed.
A further 14% were put into a "work-related activity group" to prepare them for future employment.
Only 6% of ESA claimants were exempted from work-related schemes after being judged too sick or disabled to do a job.
From October, the Department for Work and Pensions said it plans to re-test millions of existing claimants to check whether they are fit for work.
Minister for Employment Chris Grayling said: "The vast majority of people who are applying for these benefits are being found fit for work or have stopped their claim.
"These are people who under the old system would have been abandoned on incapacity benefits. It's a clear indication of why reform is so urgently needed.
"This is exactly why we are going to reassess everyone claiming incapacity benefits for their ability to work, from this October.
"They will now be given the support they need to get back to work and will be expected to look for work if they are able to do so."
The Work Capability Assessment was introduced in October 2008 along with the ESA which replaced the incapacity benefit scheme.