The Health Service Executive spent more than €318 million on agency staff in 2018, an increase of almost 9% on the 2017 figures.
The bill for agency nurses rose by over 19% amid staff shortages, which triggered strike action, though expenditure on agency doctors fell compared to the previous year.
The data is included in a HSE response to a parliamentary question from Sinn Féin's health spokespserson Louise O'Reilly.
Agency staff are estimated to cost up to 20% more than directly employed staff, though they do not receive benefits such as a permanent contract or pension entitlements.
The HSE stresses that the 2018 agency figures are draft data.
However, they indicate an ongoing and possibly increasing problem with staff shortages in some sectors.
Of last year's €318m agency spend, almost €152m was spent in the Acute Hospitals Division, but the figure in Community Health Organisations was even higher at over €166m.
The hospitals with the highest general agency spend were University Hospital Limerick (€11m), Portlaoise General Hospital (€10.7m) and our Lady of Lourdes Hospital (€9m).
With nursing staff shortages at the centre of the recent strikes, it is noteworthy that the 2018 bill for agency nurses rose by 19% to over €76m, which is almost €1.5m a week.
Agency nurses cost the Acute Hospitals Division over €29m, but the bill in the Community Health Organisations was significantly higher at €47m.
The hospitals spending most on agency nurses were Cork University Hospital (€2.7m), Mullingar General Hospital (€2.5m) and Connolly Memorial Hospital (€2.2m).
Agency doctors and dental staff - grades that also report staff shortages - cost €93.6m last year, though that was down almost 11% on 2017.
The hospitals incurring the highest bill for agency doctors or dentists were Portlaoise General Hospital (€7.1m), University Hospital Limerick (€5.7m) and Letterkenny General Hospital (€5.5m).
In relation to support services staff, the agency spend rose by almost 16% from €93.5m in 2017 to over €108m.
The Acute Hospitals Division bill at €43.5m was lower than in Community Health Organisations, where hiring agency support staff cost over €64.5m.
In 2018, the HSE also paid 26% more for agency paramedics at a cost of almost €23m.
The spend in the Community Health Organisations was higher than in acute hospitals.
In management and administrative grades, the 2018 agency spend was €16.7m - up almost 54% on 2017.
Maintenance and technical grades saw the total spend on agency workers fall from €452,000 in 2017 to €395,000 in 2018.
The HSE stressed agency pay costs are under constant review in the context of increasing demand for services, ongoing challenges on the recruitment and retention of clinical staff and the need to comply with working time legislation.
Ms O'Reilly has called on the Government to set an immediate target for converting more costly agency workers to direct employees.
She accused Minister for Health Simon Harris of being "asleep at the wheel" as the rise in the spend in agency staff continued unabated, adding that he would have to go.
She said that if a "€2bn hospital was a scandal, then a €2bn spend on agency staff since 2010 was an even bigger scandal".
Ms O'Reilly said that while removing Mr Harris was in the national interest, Fianna Fáil were abstaining in their own interest.
A spokeswoman from the Department of Health said that agency pay cost is under "constant review".
In a statement, the spokeswoman said: "Agency staff are used where there is a difficulty in recruiting and employing hospital staff and where there is a short-term critical service need.
"Agency is also used for flexibility to allow for variation in activity and as required to meet patient demand needs.
"Efforts have repeatedly been made to address this issue and there has been some success, particularly in the acute sector."
The Minister for Finance has said that figure shows why the recent Labour Court recommendation in the nurses' dispute over pay and conditions looks at ways to reduce the use of agency staff.
Speaking on RTÉ's News at One, Paschal Donohoe said the use of agency staff was not exclusive to the Irish health service.