More than £30m has been spent on taxis for NHS patients since 2008 thanks to a shortage of official non-emergency transport, according to the BBC.
The corporation obtained the data through a Freedom of Information request to which ambulance trusts in England, Wales and Northern Ireland responded.
However, health chiefs said patients were not at risk, even though the figures cover the transfer of patients too ill to travel alone, such as those with broken limbs or receiving chemotherapy. Bosses admitted they aimed to lower the use of taxis with concerns that they were not giving value for money.
The North West Ambulance Service, which along with other trusts said it was reducing reliance on taxis, spent the most, with - £9.9m since April 2008.
Some trusts gave data on the most costly taxi journeys they forked out for, including two £700-plus fares, one for a 184-mile trip from Cambridgeshire to Bristol after a discharge from Papworth Hospital. The second was a drive of 151 miles from Chase Farm Hospital in north London to Shrewsbury, Shropshire.
NHS chiefs must decide who transports patients, said the Department of Health.