Unions have reacted angrily to reports that GP practices could be partially floated on the stock market - making profit for both doctors and private companies.
An investigation by Channel 4 News has discovered the Health and Social Care Bill, currently going through parliament, contains few safeguards to protect patients from conflicts of interest.
The reforms will see about £80 billion of the NHS budget handed to GPs, who will buy in services.
The investigation has found evidence of GPs with shares in private companies which provide services to the NHS for profit.
At present, primary care trusts (PCTs) decide what care to buy for patients but in future GPs will decide, meaning they can send patients to companies in which they have a stake.
A leaked document obtained by Channel 4 News also shows how one private company plans to work with groups of GPs under the Government's reforms. It sets out how both the company, in this case Integrated Health Partners (IHP), and GPs could make a profit. It suggests that if 5% is saved from patient budgets, this can be shared as profit between GPs and the company.
IHP is involved with a number of GP consortia in Surrey and aims to list on the stock market in three to five years, Channel 4 reported.
The head of IHP, Dr Oliver Bernath, did not deny the potential for profits but told Channel 4 there would be a balance, with points for outcomes, meaning savings would not be made at the expense of providing quality patient care.
He told The Guardian: "The whole NHS is £80 billion in spending and if GPs can take underspends then we can get a large audience fairly quickly. Investors will find it very attractive fairly quickly."
Unite general secretary Len McCluskey said: "The fact that family doctors could be set for windfall profits under the Government's plans, which will see them controlling £80 billion of the NHS budget, will horrify and alarm the public."