The biggest shake up of the National Health Service in England, since its formation more than 60 years ago, comes into effect on Monday.
GPs will run local health services, leading new teams known as Clinical Commissioning Groups, and they will be supported by health professionals such as local hospital doctors and nurses.
The teams will decide on which health issues are a priority in their area, and where to send patients for treatment in NHS or private facilities.
They will control around 60% of the NHS budget in England but will not be in charge of major services like complex surgery and rare cancers.
But as our Political Correspondent Libby Wiener reports, ITV News has learned that only half the new groups are fully ready for Monday's reforms.
Only half of the NHS’s new regional health service bodies will be fully ready to start work when the changes come into effect on Monday.
Just 106 of the 211 Clinical Commissioning Groups (CCGs) are "fully authorised", said NHS England.
The new groups are led by GPs and other clinicians who will take on responsibility for commissioning local hospital, community health and mental health services.