The HSE has spent almost €90m on taxis since 2012, according to figures released under the Freedom of Information Act.
The data shows the executive has spent almost €16m on taxi services this year alone.
Since the start of 2012 the HSE has spent €50,000 a day on taxi fares.
The figures show a massive spend by the Executive, with two taxi companies getting paid more than a million euro each for journeys made this year alone.
In total, 37 companies have been paid more than €100,000 by the HSE in 2016.
The Executive has defended the spend, saying it is more cost-effective than buying their own fleet of cars to transport patients who are not acutely ill.
They say the use of taxis also allows them to deal with variable demand at different times of the year.
The biggest spend in the past five years was in 2012 when the HSE spent more than €20m on taxis.