Delays and costs of the multi-billion pound NHS information technology upgrade mean its future is "not looking good", a group of MPs has said.
The report says the IT programme is behind schedule
The Commons public accounts committee, headed by Edward Leigh MP, said urgent action was needed to ensure an adequate service was provided.
Its report said the electronic patient clinical record, central to the project, was already two years late.
But the government said the MPs' report was based on out-of-date information.
The upgrade of the NHS IT programme is set to link more than 30,000 GPs in England to nearly 300 hospitals by 2014, and includes an electronic medical records system and e-prescriptions.
But the MPs warn costs could rise to at least £12.4 billion.
In the report, they say the stake for the IT programme are high: "If it succeeds in its aims, the programme could revolutionise the way the NHS in England uses information, and make significant improvements to the quality of patient care.
"But if it fails, it could set back IT developments in the NHS for years, and divert money and staff time from frontline patient services."
Mr Leigh added: "Urgent remedial action is needed at the highest level if the long-term interests of NHS patients and taxpayers are to be protected.
"The programme is not looking good. And, four years down the line, the costs and benefits for the local NHS are unclear."
The report said suppliers are struggling to provide effective computer systems that the NHS can use, and that the whole scheme is slipping behind schedule.
Mr Leigh said the Department of Health should "get a grip" on what it and the NHS were spending.
He said that if suppliers could not resolve problems with the patient records system - which will contain details of more than 50 million people - local trusts should be freed to develop alternatives.
Committee member Richard Bacon called for the scrapping of Connecting for Health, the agency responsible for the IT programme.
"It is a nightmare organisation and I think the NHS would be better off without it."
James Johnson, chairman of the British Medical Association, said: "Although much work has been done more recently to involve doctors, many remain unconvinced that the system will be fit for purpose."
However health minister Lord Hunt criticised the MPs' report. "This is based on a National Audit Office (NAO) report that is now a year out of date.
"Since then substantial progress has been made and the NAO recommendations have already been acted on."
He said costs of the programme had not escalated, electronic prescriptions were now available and digital X-rays were increasingly being used.
Shadow health minister Stephen O'Brien, said: "Doctors and nurses were left out of the planning and design of the NHS IT programme and that has been a huge problem."
And Liberal Democrat health spokesman Norman Lamb said the report contained "damning evidence" about failures of the IT programme.