Clinical trials in Ireland: the numbers behind 2,691 studies

What the register counts, and what open means

This report reads every study on ClinicalTrials.gov, the register run by the US National Library of Medicine, that lists a site in Ireland. Our snapshot was taken on 30 September 2026 and found 2,691 such studies registered since 2010. The live Irish clinical trial register refreshes nightly, so its counts move a little from day to day.

Open means different things in different reports, so we define it. A study is open to new participants when its status is recruiting, not yet recruiting, or enrolling by invitation. That gives 360 studies. If you also count studies that are active but no longer recruiting, the figure rises to 603. Both numbers are correct; they answer different questions, and the second is the one our register page shows as studies in scope.

The 311 studies marked unknown are a feature of the register, not of Irish research. A sponsor that stops updating a record after its completion date leaves it in that state, and readers should treat most of them as finished. The 194 terminated and 16 withdrawn studies, 7.8 per cent of the total, are the ones that stopped early or never started, usually for recruitment or funding reasons rather than safety.

How many clinical trials in Ireland start each year

Study starts have held in a band of roughly 125 to 170 a year for a decade. The peak was 2021, with 172 studies starting at an Irish site, of which 90 were industry sponsored and 79 ran only in Ireland. The years either side were quieter: 128 starts in 2020, the first pandemic year, and 134 in 2022. In 2025, 141 studies started: 76 industry, 65 academic, 124 interventional, and 47 of them Phase 3. The first nine months of 2026 show 64 starts, 24 industry sponsored and 40 academic, with the year still open.

The industry share has drifted down. In 2017 industry sponsored 88 of 144 starts, 61 per cent; in 2024 it sponsored 63 of 143, 44 per cent, before recovering to 54 per cent in 2025. Academic and hospital sponsors filled the gap, which is consistent with the growth of the national cancer and clinical research networks over the period.

Completions tell a similar story. The register records 113 studies completing in 2023, 94 in 2024, 86 in 2025 and 44 so far in 2026. Phase 3 studies, the large confirmatory trials that support a licence, make up 907 of all 2,691 studies and 102 of the 360 currently open to participants. Among open studies the phase mix is 185 with no phase (device, behavioural and observational studies), 102 Phase 3, 30 Phase 2, 21 Phase 1/2, 9 Phase 2/3, 7 Phase 1 and 6 Phase 4.

Ireland-only trials and multinational trials

Of the 2,691 studies, 910 list Ireland as the only country. These are overwhelmingly academic and hospital studies: a dietary intervention in Cork, a surgical technique at a Dublin hospital, a screening study across a hospital group. The rest, 1,781 studies, are multinational, and in those Ireland is usually one country among many. The average study in the register lists 1.9 Irish sites, and among industry studies the median planned enrolment is 382 participants across all countries.

Ireland-only starts have grown as a share of the total. In 2017, 44 of 144 starts were Ireland-only, 31 per cent. In 2023 the figure was 76 of 155, 49 per cent, and in 2024 it was 67 of 143, 47 per cent. More of what starts in Ireland now is designed and run in Ireland.

Most studies, 2,210, are interventional, meaning participants receive a treatment or procedure under the protocol. A further 472 are observational and 9 are expanded access programmes that give patients a medicine outside a trial.

Who sponsors clinical trials in Ireland

Industry is the largest single sponsor class, with 1,491 studies. Universities, hospitals and research networks account for 1,056, networks for 110, other government bodies for 23 and the US National Institutes of Health for 11.

Across the whole period, University College Cork leads with 112 studies as lead sponsor, followed by University College Dublin with 102, the Royal College of Surgeons in Ireland with 75, Novartis with 72, Bristol-Myers Squibb with 71, Cancer Trials Ireland with 70, Trinity College Dublin with 69 and Merck Sharp and Dohme with 60.

The picture over the last five years is more academic. The Royal College of Surgeons in Ireland tops that list with 46 studies, then University College Dublin with 45, University College Cork with 42, Trinity College Dublin with 26, Merck Sharp and Dohme with 25 and the University of Limerick with 21. Bristol-Myers Squibb and AbbVie follow with 11 each.

Two Irish research organisations stand out in the sponsor and collaborator fields. Cancer Trials Ireland, the national cooperative cancer research group, appears on 89 studies, 10 of them open, with its most recent record dated April 2026. Atlantia Clinical Trials in Cork, which runs food and nutraceutical studies, appears on 72, 6 of them open. The clinical research facilities at St James's Hospital and University Hospital Galway appear on 19 and 15 studies respectively.

Which conditions and hospitals lead

Breast cancer is the single most studied condition, with 75 studies, followed by cystic fibrosis with 40, which reflects Ireland's incidence of the condition, among the highest in the world. Prostate cancer and type 2 diabetes each account for 34 studies, Crohn's disease and rheumatoid arthritis for 33 each, and multiple myeloma for 30. Cancer in its various forms is the largest therapeutic area by a wide margin once breast, prostate, myeloma and general cancer studies are added together.

Dublin hospitals dominate the site list. St James's Hospital appears on 247 studies, St Vincent's University Hospital on 217, Beaumont Hospital on 213, the Mater Misericordiae University Hospital on 160 and Tallaght University Hospital on 123. Outside the capital, University Hospital Galway is listed on 216 studies, Cork University Hospital on 212 and University Hospital Waterford on 95. Counting every site mention, Dublin appears 2,794 times, Cork 725, Galway 509, Limerick 248, Waterford 162 and Sligo 53.

The concentration matters for patients outside the main cities. A person in Donegal or Kerry is far more likely to be asked to travel to a trial site than a person in Dublin, and the register's site list is the quickest way to see which studies have opened a site nearby.

Ireland in the EU register

Since January 2023 every new clinical trial of a medicine in the EU must be submitted through the Clinical Trials Information System, CTIS, run by the European Medicines Agency. Our feed of CTIS public records began on 2 September 2025. In that period CTIS has published 12,494 trial records across the EU, of which 85 list Ireland as a participating country, and 73 of those were published in the last twelve months. You can browse them on our EU clinical trial register.

The two registers overlap but are not the same. ClinicalTrials.gov includes observational studies, device trials and older trials that CTIS never held, which is why the ClinicalTrials.gov count is far larger. CTIS, on the other hand, is the legal record for medicine trials in the EU, and a trial that recruits in Ireland and another EU country should appear in both.

What the numbers say about Ireland as a trial location

Three things stand out. First, Ireland is a steady rather than a growing location for industry trials: industry starts have moved between 63 and 90 a year since 2017 without a clear trend. Second, academic research has grown, both in absolute starts and as a share, with the universities and the Royal College of Surgeons now the most active sponsors of the last five years. Third, activity is concentrated in five hospitals in Dublin, Cork and Galway, which host the great majority of industry sites.

For a company deciding where to place a site, the register shows established oncology, cystic fibrosis, diabetes and inflammatory disease networks with long track records. For a patient, it shows that most open studies are Phase 3 or late-phase, and that the national cancer network is the most reliable route to a cancer trial.

Method and sources

We queried the ClinicalTrials.gov API for all studies with a location country of Ireland and took a snapshot on 30 September 2026 at 05:16 UTC. Status, phase, sponsor class, study type, start date and enrolment are the sponsor's own entries. Sponsor and hospital names are grouped as the register spells them, so a hospital recorded under two spellings appears as two sites. Open to new participants means the status is recruiting, not yet recruiting or enrolling by invitation; studies in scope adds active, not recruiting. Ireland-only means Ireland is the only location country. The year of a study is its start date; the completed year uses the primary completion date. Percentages are rounded to the nearest whole number. CTIS figures come from the EMA's public CTIS data feed.

Reuse and citation: this analysis is published by Priya Life Science under CC BY 4.0. The underlying ClinicalTrials.gov records are US government public data and CTIS records are reused under the EMA legal notice. Use the citation box below; our methodology page explains how all our registers are built, and any correction is logged on our corrections page.