| Rank | Athlete | College | Mark | Date | Championship | Race | Venue |
|---|---|---|---|---|---|---|---|
| 198 | Philip Beattie | QUB | 51.00 | 1986-05-02 to 1986-05-03 | T&F | 400mH | Santry & College Park |
| 112 | Brian Liddy | TCD | 51.50 | 1999-04-24 | T&F | 400mH | Mary Peters |
| 203 | Philip Beattie | QUB | 52.20 | 1984-05-04 to 1984-05-05 | T&F | 400mH | Belfield |
| 119 | James Matthews | Guest | 52.75 | 1999-04-24 | T&F | 400mH | Mary Peters |
| 214 | Clive Beattie | QUB | 52.90 | 1979-05-04 to 1979-05-05 | T&F | 400mH | Belfield |
| 199 | Denis Finnerty | TCD | 52.90 | 1986-05-02 to 1986-05-03 | T&F | 400mH | Santry & College Park |
| 175 | Brian Liddy | UCD | 53.14 | 1996-04-19 to 1996-04-20 | T&F | 400mH | Antrim Forum |
| 194 | J.J. Barry | TCD | 53.22 | 1988-04-29 to 1988-04-30 | T&F | 400mH | Santry |
| 39 | Brian Liddy | IUAA | 53.27 | 1999-06-22 | Celtic T&F | 400mH | Antrim Forum |
| 294 | John Fagan | DCU | 53.29 | 2010-04-24 | T&F | 400mH | Santry |
| 113 | Colin Byrne | WIT | 53.31 | 1999-04-24 | T&F | 400mH | Mary Peters |
| 176 | Jeremy Lyons | Waterford RTC | 53.43 | 1996-04-19 to 1996-04-20 | T&F | 400mH | Antrim Forum |
| 195 | J.J. Barry | TCD | 53.50 | 1987-05-08 to 1987-05-09 | T&F | 400mH | Antrim Forum |
| 90 | Colin Byrne | DCU | 53.51 | 2003-04-26 | T&F | 400mH | Dangan & Tullamore Track |
| 287 | John Fagan | DCU | 53.57 | 2010-04-23 | T&F | 400mH SF 1 | Santry |
| 25 | Matthew Douglas | NI U23 | 53.60 | 1996-06-25 | Celtic T&F | 400mH | Antrim Forum |
| 217 | Clive Beattie | QUB | 53.60 | 1978-05-05 to 1978-05-06 | T&F | 400mH | Mary Peters |
| 257 | Jonathan Miller | Guest | 53.61 | 2007-04-14 | T&F | 400mH | Santry |
| 204 | J.J. Barry | UCD | 53.70 | 1983-05-06 to 1983-05-07 | T&F | 400mH | Upper Malone Road |
| 124 | James Matthews | Guest | 53.75 | 1999-04-23 to 1999-04-24 | T&F | 400mH SF 2 | Mary Peters |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| John Dillon | TCD | 57.20 | 1970-05-09 | Belfast |
| John Dillon | TCD | 55.00 | 1971-05-07 to 1971-05-08 | Mardyke |
| Paul Beattie | QUB | 53.90 | 1974-05-03 to 1974-05-04 | Belfield |
| Clive Beattie | QUB | 53.60 | 1978-05-05 to 1978-05-06 | Mary Peters |
| Clive Beattie | QUB | 52.90 | 1979-05-04 to 1979-05-05 | Belfield |
| Philip Beattie | QUB | 52.20 | 1984-05-04 to 1984-05-05 | Belfield |
| Philip Beattie | QUB | 51.00 | 1986-05-02 to 1986-05-03 | Santry & College Park |
| Athlete | College | Mark | Date | Venue |
|---|---|---|---|---|
| A. O'Leary | UCC | 68.00 | 1981-05-01 to 1981-05-02 | Plassey |
| A. Lyons | TCE | 66.20 | 1983-05-06 to 1983-05-07 | Upper Malone Road |
| Barbara Johnson | UCC | 63.90 | 1984-05-04 to 1984-05-05 | Belfield |
| Mary Nolan | TCD | 63.50 | 1985-05-03 to 1985-05-04 | Mardyke |
| A. Leonard | UU | 61.80 | 1986-05-02 to 1986-05-03 | Santry & College Park |
| Brona Furlong | DCU | 61.39 | 2008-04-19 | Irishtown Stadium & Belfield |
| Brona Furlong | DCU | 60.52 | 2009-04-25 | Plassey |
| Brona Furlong | DCU | 59.41 | 2010-04-24 | Santry |