| Rank | Athlete | College | Mark | Date | Championship | Race | Venue |
|---|---|---|---|---|---|---|---|
| 570 | Robert Daly | UCD | 47.25 | 2001-04-21 | T&F | 400m | Santry & Belfield |
| 620 | Kieran Finn | NIHEL | 47.60 | 1984-05-04 to 1984-05-05 | T&F | 400m | Belfield |
| 498 | Tomas Coman | UL | 47.66 | 2003-04-26 | T&F | 400m | Dangan & Tullamore Track |
| 621 | Mark Roughan | QUB | 47.70 | 1984-05-04 to 1984-05-05 | T&F | 400m | Belfield |
| 610 | J.J. Barry | TCD | 47.70 | 1988-04-29 to 1988-04-30 | T&F | 400m | Santry |
| 630 | Clive Beattie | QUB | 47.70 | 1980-05-02 to 1980-05-03 | T&F | 400m | Mardyke |
| 416 | David Gillick | IUAA | 47.70 | 2003-06-10 | Celtic T&F | 400m | Antrim Forum |
| 507 | Tomas Coman | WIT | 47.77 | 1999-04-23 to 1999-04-24 | T&F | 400m | Mary Peters |
| 497 | David Gillick | DIT | 47.78 | 2003-04-26 | T&F | 400m | Dangan & Tullamore Track |
| 569 | Gordon Kennedy | AIT | 47.80 | 2005-04-23 | T&F | 400m | Irishtown Stadium & Belfield |
| 633 | Clive Beattie | QUB | 47.80 | 1979-05-04 to 1979-05-05 | T&F | 400m | Belfield |
| 376 | Brian Forbes | IUAA | 47.80 | 1997-06-24 | Celtic T&F | 400m | Antrim Forum |
| 448 | Gordon Kennedy | AIT | 48.04 | 2000-04-15 | T&F | 400m | Plassey |
| 388 | Brian Forbes | IUAA | 48.08 | 1999-06-22 | Celtic T&F | 400m | Antrim Forum |
| 623 | Kieran Finn | NIHEL | 48.10 | 1983-05-06 to 1983-05-07 | T&F | 400m | Mary Peters |
| 345 | Paul McKee | Guest | 48.20 | 2005-06-07 | Celtic T&F | 400m | Antrim Forum |
| 629 | Brian Dunne | UCD | 48.30 | 1981-05-01 to 1981-05-02 | T&F | 400m | Plassey |
| 622 | Brian Dunne | UCD | 48.30 | 1984-05-04 to 1984-05-05 | T&F | 400m | Belfield |
| 382 | Brian Forbes | IUAA | 48.30 | 1998-06-23 | Celtic T&F | 400m | Antrim Forum |
| 383 | Paul McKee | NI U23 | 48.30 | 1998-06-23 | Celtic T&F | 400m | Antrim Forum |
| 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 |
| 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 |
| Maura Prendiville | UCC | 60.68 | 1996-02-09 to 1996-02-10 | 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 |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| R. Hall | QUB | 51.90 | 1970-05-09 | Belfast |
| Dennis O'Connell | UCD | 51.00 | 1971-05-07 to 1971-05-08 | Mardyke |
| John Dillon | TCD | 49.10 | 1972-05-05 to 1972-05-06 | Santry & College Park |
| Tim Crowe | TCE | 48.70 | 1974-05-03 to 1974-05-04 | Belfield |
| Paul Duffy | UCD | 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 | Belfast |
| Elaine Kelly | UCC | 58.00 | 1974-05-03 to 1974-05-04 | Belfield |
| A. Lyons | TCE | 54.00 | 1983-05-06 to 1983-05-07 | Mary Peters |
| Karen Shinkins | WIT | 53.50 | 1999-04-24 | Mary Peters |