| Rank | Athlete | College | Mark | Date | Championship | Race | Venue |
|---|---|---|---|---|---|---|---|
| 1 | Robert Daly | UCD | 47.25 | 2001-04-21 | T&F | 400m | Santry & Belfield |
| 2 | Mark English | UCD | 47.56 | 2013-04-12 to 2013-04-13 | T&F | 400m | Mardyke & Bishopstown |
| 3 | Kieran Finn | NIHEL | 47.60 | 1984-05-04 to 1984-05-05 | T&F | 400m | Belfield |
| 4 | Tomas Coman | UL | 47.66 | 2003-04-26 | T&F | 400m | Dangan & Tullamore Track |
| 5 | Clive Beattie | QUB | 47.70 | 1980-05-02 to 1980-05-03 | T&F | 400m | Mardyke |
| 6 | David Gillick | IUAA | 47.70 | 2003-06-10 | Celtic T&F | 400m | Antrim Forum |
| 7 | John J. "J.J." Barry | TCD | 47.70 | 1988-04-29 to 1988-04-30 | T&F | 400m | Santry |
| 8 | John J. "J.J." Barry | TCD | 47.70 | 1989-05-05 to 1989-05-06 | T&F | 400m | Mary Peters |
| 9 | Mark Roughan | QUB | 47.70 | 1984-05-04 to 1984-05-05 | T&F | 400m | Belfield |
| 10 | Michael Cooke | QUB | 47.74 | 1989-05-05 to 1989-05-06 | T&F | 400m | Mary Peters |
| 11 | Philip Snoddy | QUB | 47.74 | 1988-04-29 to 1988-04-30 | T&F | 400m | Santry |
| 12 | Tomas Coman | WIT | 47.77 | 1999-04-23 to 1999-04-24 | T&F | 400m | Mary Peters |
| 13 | Thomas Barr | UL | 47.77 | 2013-02-01 | Indoors | 400m | Athlone Institute of Technology |
| 14 | David Gillick | DIT | 47.78 | 2003-04-26 | T&F | 400m | Dangan & Tullamore Track |
| 15 | Clive Beattie | QUB | 47.80 | 1979-05-04 to 1979-05-05 | T&F | 400m | Belfield |
| 16 | Brian Forbes | IUAA | 47.80 | 1997-06-24 | Celtic T&F | 400m | Antrim Forum |
| 17 | Gordon Kennedy | AIT | 47.80 | 2005-04-23 | T&F | 400m | Irishtown Stadium & Belfield |
| 18 | Gordon Kennedy | AIT | 48.04 | 2000-04-15 | T&F | 400m | Plassey |
| 19 | Brian Forbes | IUAA | 48.08 | 1999-06-22 | Celtic T&F | 400m | Antrim Forum |
| 20 | Kieran Finn | NIHEL | 48.10 | 1983-05-06 to 1983-05-07 | T&F | 400m | Mary Peters |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| Paul Kellagher (OYD) | UL | 50.70 | 1993-02-12 | Nenagh Olympic Stadium |
| Keelan Conlon | UCD | 49.16 | 1994-01-21 | Nenagh Olympic Stadium |
| David McCarthy | UL | 48.88 | 2002-12-07 | Nenagh Olympic Stadium |
| David McCarthy | UL | 48.46 | 2004-12-04 | Nenagh Olympic Stadium |
| Thomas Barr | UL | 47.77 | 2013-02-01 | Athlone Institute of Technology |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| Louise Maher | UCD | 63.00 | 1993-02-12 | Nenagh Olympic Stadium |
| Aisling McGuinness | UCC | 61.44 | 1994-01-21 | Nenagh Olympic Stadium |
| Kerry Dillon | Waterford RTC | 60.20 | 1995-02-10 | Nenagh Olympic Stadium |
| Karen Shinkins | WIT | 57.00 | 1996-12-13 to 1996-12-14 | Nenagh Olympic Stadium |
| Karen Shinkins | WIT | 55.66 | 1997-12-13 | Nenagh Olympic Stadium |
| Karen Shinkins | WIT | 55.00 | 1998-12-12 | Nenagh Olympic Stadium |
| Christine McMahon | QUB | 54.77 | 2013-02-01 | Athlone Institute of Technology |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| R. Hall | QUB | 51.50 | 1970-05-09 | Belfield |
| Denis O'Connell | UCD | 51.00 | 1971-05-07 to 1971-05-08 | Mardyke |
| John James Dillon | TCD | 49.10 | 1972-05-05 to 1972-05-06 | Santry & College Park |
| Tim Crowe | NCPE | 48.70 | 1974-05-03 to 1974-05-04 | Belfield |
| Maurice Power | UCC | 48.60 | 1976-04-30 to 1976-05-01 | Plassey |
| Clive Beattie | QUB | 48.60 | 1978-05-05 to 1978-05-06 | Mary Peters |
| Clive Beattie | QUB | 47.80 | 1979-05-04 to 1979-05-05 | Belfield |
| Clive Beattie | QUB | 47.70 | 1980-05-02 to 1980-05-03 | Mardyke |
| Kieran Finn | NIHEL | 47.60 | 1984-05-04 to 1984-05-05 | Belfield |
| Robert Daly | UCD | 47.25 | 2001-04-21 | Santry & Belfield |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| Fionnuala Lysaght | UCG | 61.90 | 1970-05-09 | Belfield |
| Elaine Kelly | UCC | 58.00 | 1974-05-03 to 1974-05-04 | Belfield |
| Ann Lyons | TCE | 54.00 | 1983-05-06 to 1983-05-07 | Mary Peters |
| Karen Shinkins | WIT | 53.50 | 1999-04-24 | Mary Peters |