The government's contentious care.data project is to go ahead with a pilot programme in four areas of England.
The data sharing programme will start in participating GP surgeries in four clinical commissioning group (CCG) areas: Leeds North, West, South and East, Somerset, West Hampshire and Blackburn with Darwen.
A panel featuring representatives from the British Medical Association (BMA) and voluntary sector partners chose the four areas.
The Independent Information Governance Oversight Panel (IIGOP) will monitor pathfinder practices taking part in the care.data trials.
Initially due to start in April, care.data aims to set up a database of people's GP medical records. Privacy concerns from patient groups put the project on hold for six months.
The NHS said a shortlist of the 265 GP practices in these areas will be announced "in due course".
Tim Kelsey, NHS England National Director for Patients and Information, said his organisation needed to be "clearer about the care.data programme and that we need to provide more support to GPs to communicate the benefits and the risks of data sharing with their patients, including their right to opt out."
He added there were "huge benefits" to be had from the programme and wanted to make sure that "we get it absolutely right".
"We already collect and share information in so many walks of life. The pathfinder stage is another step on the way to creating a more substantial picture of our nation's health so we can improve care for patients," he said.
"Since February we have been listening to the views of the public, GPs and other important stakeholders to hear their concerns about data sharing."
According to pressure group Med Confidential, fears over privacy in the wake of the programme remain.
"Identifiable medical information will be extracted from the GP record of every man, woman and child in England," said Phil Booth, head of Med Confidential, in a blog post. "This data will be centralised, linked with information taken from other parts of the NHS and made available to an open-ended array of organisations and companies for ill-defined purposes."
