The news comes alongside the announcement that healthcare provider Care UK is to be acquired by private equity firm Bridgepoint.
The Assura Group announced it has sold a 75.1% stake in its medical services business, which serves more than three million patients, to Virgin Healthcare.
Sir Richard Branson, founder of the Virgin Group, said healthcare is a sector he has been ‘extremely interested in entering for some time'.
He said: ‘I am excited that Virgin and Assura will continue to develop this business, working alongside our NHS partners to bring excellent, high quality services right to the heart of our patients' communities.'
Richard Burrell, chief executive officer of Assura, said: ‘With its strong brand and financial position, Virgin is the ideal organisation to take Assura Medical's business to the next stage of its development.'
Meanwhile Care UK, which operates a number of primary care services including GP practices, walk-in centres and GP out-of-hours services, has been acquired by private equity firm Bridgepoint.
Care UK said the front line provision and management of care services will be unaffected by the move.
Mike Parish, chief executive of Care UK, said: 'Care UK has built a leading UK business in the provision of social care services and is a market leading independent provider of healthcare services to the NHS.
'I believe this development is good news for the company and for our customers, patients and service users.'