Ireland's public acute hospitals may need up to 15,500 more staff within 13 years, according to a new ESRI report.
The report on workforce requirements said that workforce needs for all staff categories are projected to increase substantially by 2035.
This is driven by large projected increases in older age groups.
It said there will need to be particularly large increases for health and social care professionals, notably occupational therapists and speech and language therapists, particularly for older people in hospital.
Extra staff will also be needed to help cut waiting lists.
The report said that some projected increases in staff may be offset by increasing the proportion of care delivered by assistant grades.
The report put the staff increase needs at between 12,418 and 15,491.
It suggested that up to 3,236 more medical staff may be needed, up to 8,868 more nursing and midwifery staff and up to 3,277 extra healthcare assistants.
There will also be a need for up to 166 more dieticians, 214 occupational therapists, 494 physiotherapists, 118 speech and language therapists and 148 social workers.
The ESRI said that workforce planning will be key to delivering on the Sláintecare reforms.
But it warned that increasing the future workforce supply to the levels recommended will be a challenge for policymakers, given the recognised difficulties with staff recruitment and retention nationally and internationally.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
The National Director of Human Resources at the HSE, Ann Marie Hoey, said that the HSE continues to "recruit significant numbers of staff".
Speaking to RTÉ's News at One, Ms Hoey said: "This report published today enables us now to plan for the workforce and also the financial projections that would be needed each year and also the infrastructural needs.
"So what this does is inform our engagement with government departments in relation to the financial planning that will be needed year on year and as you'll be aware each year the HSE agrees a national service plan with our government department, the Department of Health, and this report will inform the funding we will need in next year and future years to meet the demands."
She also said that the projections of how many staff will be needed will give the education sector an indication of how many college places will be needed to train sufficient numbers for the health service.