Trauma patients taken to new John Radcliffe Hospital unit
Patients in the Thames Valley with life-threatening injuries will now be taken by ambulance to Oxford's John Radcliffe Hospital.
The hospital's new major trauma centre will provide access to specialist teams and equipment, an Oxford University Hospitals NHS Trust spokesman said.
If it is not possible to get there within 45 minutes then patients will be taken to their nearest hospital first.
The unit is one of five new major trauma centres in the South.
The centres, which also include Plymouth, north Bristol, Southampton and Brighton, will have consultants available 24 hours a day, seven days a week.
They form part of an England-wide network of 22 currently being set up.
Saving more lives
Dr James Mapstone, clinical director of acute care for NHS South of England, said ambulance crews had had extra training.
"A huge amount of work has gone into developing this new model of care," he said.
"I am confident that having the highest level of expertise, experience and equipment in one place will help us save more lives."
Major trauma patients are those who are most likely to die, such as people with serious gun and knife wounds or multiple injuries from car crashes.
The specialist hub in Oxford will care for trauma patients from the Thames Valley including Oxfordshire, Buckinghamshire, parts of Gloucestershire, Wiltshire, Berkshire and Northamptonshire.
A report by the National Audit Office in 2010 suggested the centres could save an extra 450 to 600 lives in England every year.