The revamp of NHS IT has been fraught with problems
The Conservatives have promised huge cost savings for the NHS by scrapping government plans for a central database of patient records.
Proposals include electronic medical notes being stored locally by GPs and hospitals and patients having online access to their medical records.
IT firms such as Google or Microsoft could host the information.
But the government said the Conservatives' plans raised concerns about patient confidentiality.
The Tories are promising NHS trusts a choice of computer systems, rather than having a single one imposed.
Every patient would have a username and password and could update their records with information like blood pressure and cholesterol levels.
Shadow health minister Stephen O'Brien insisted these separate systems would be "inter-operable", allowing information to be accessed in different locations.
He said: "You want to have your data held locally and that should be with the person you trust most in the health service, which will be your GP."
Mr O'Brien told the BBC: "We want to give patients the ability to give themselves greater control over their information."
He added: "If we hold the data locally it's more likely to be protected than within this massive [NHS] database...
"There's always a need to protect data, whether it's in the public or private sector.
"What has to happen is to focus on patients' health and improve their outcomes."
The £12bn NHS programme in England - the world's largest civilian IT scheme - has been dogged by problems since its launch in 2002.
It aims to replace hundreds of different computer systems in hospitals and GP practices with compatible versions which allow staff to access patients' medical records.
It is thought the project is five years behind schedule.
Although some parts have been implemented successfully, there have been problems in upgrading computer systems in hospitals and setting up the electronic patient record.
The Tories say contracts in place with IT service providers - two out of four of whom have already pulled out - should be brought to a halt and renegotiated to "prevent further inefficiencies".
But Health Minister Ann Keen said: "The Tories need to make it very clear how their plans will ensure patient confidentiality.
"We have already set out our plans to give patients greater access to health information, for example through Healthspace where patients can see their summary care record."
A Department of Health spokesman said: "Patients are now directly benefiting from the modernisation of NHS IT - including being able to make their first outpatient appointment through Choose and Book, new digital images and a new electronic prescriptions service."
He added that the programme was already being delivered locally, with "detailed care records" continuing to be held in an electronic form.
The government has made it clear to the companies contracted to deliver the upgrades that it expects further significant progress by the end of November, he said.