The Royal Free employed extra staff to handle the faulty system
A new NHS computerised medical records system on trial at a London hospital has been criticised by a hospital boss for causing "heartache and hard work".
Andrew Way, chief executive of London's Royal Free Hospital, said technical problems had cost the trust £10m and meant fewer patients could be seen.
The Department of Health said lessons had been learnt from the trial.
The England scheme, part of a £12bn IT upgrade, aims to put 50 million patient records on a secure database by 2014.
The Royal Free, one of a number of early adopters of e-records, has been using the system since last summer.
The project, restricted to England, has been one of the most controversial aspects of the overall 10-year IT programme, which also involves an online booking system, digital imaging for X-rays and electronic prescriptions.
Mr Way said the cost of the problems had meant the hospital had been unable to invest in new equipment.
He also said technical glitches had caused more work for staff and meant out-patients' bookings were taking four times as long.
As a result, the hospital has had to employ another 40 administrative staff to handle the extra workload, he added.
The faulty system had also prevented the hospital from billing other parts of the NHS for treatment.
Mr Way said: "I think it is very disappointing that the work we had to do as a trust has caused our staff so much heart-ache and hard work.
"Many of the medical staff are incredibly disappointed with what we have got.
"I have personally apologised for the decision to implement the system before we were really clear about what we were going to receive.
"I had been led to believe it would all work."
However, he said he still believed in the idea of replacing paper records with an electronic system, but it would need more work to get it right.
Overall, the hospital has spent an extra £4m to get the system working.
On top of this, Mr Way estimates the Royal Free has lost £6m because of fewer patients and glitches with the system, meaning it was unable to bill other parts of the NHS for work done.
Nigel Edwards, of the NHS Confederation, which represents most health service organisations, said: "This isn't the first hospital to have very significant problems with implementation.
E-records should allow a patient's medical records, currently held by GPs, to be accessed by a range of NHS staff
It is part of a 10-year, £12bn upgrade of the NHS IT network, which will also see online bookings and e-prescriptions
However there are fears about the confidentiality of patient records
"Hospitals need to be able to tailor what they have got to their needs, rather than being given this one-size-fits-all solution."
Michael Summers, vice chairman of the Patients' Association, said the failure of a trust's IT system potentially let patients down in many ways.
"For example, what happens is that their medical records get lost. The patients have to wait longer for their treatment because of the muddle.
"And in some cases, operations are postponed or patients are - the wrong patients are led to the surgery."
A Department of Health spokesman said: "Many elements of the programme are complete, and patients and clinicians are now beginning to see the benefits these systems bring to improve patient care.
"We are learning lessons from the deployment at the Royal Free of Cerner Millennium, which now has an effective patient record system, and we expect these lessons to help us improve further deployments."
Prime Minister Gordon Brown vigorously defended the NHS IT project at a meeting of Commons select committee chairmen on Thursday.
He said: "For all the problems that a huge project like that has created, you cannot say that that is not an advance."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.