Start Time: 02:25pm
WR 43.18 Michael Johnson (USA)
ER 44.33 Thomas Schonlebe (GDR)
IR 45.12 David Gillick (IRL)
MR 45.32 Brandon Simpson (JAM)
| Place | No. | Lane | Name | Country | YOB | Official Time | Reaction Time |
| 1 | 109 | 7 | Fergus Hannon | Ireland | 49.17 | 0,312 | |
| 2 | 113 | 3 | Eoin Mulhall | Ireland | 90 | 49.70 | |
| 3 | 10 | 5 | Barry Upton | Ireland | 86 | 49.85 | 0,265 |
| 4 | 147 | 4 | Cathal Owens | Ireland | 49.89 | 0,284 | |
| 5 | 153 | 8 | Alan Whelan | Ireland | 50.24 | ||
| 6 | 116 | 2 | Patrick Maher | Ireland | 51.12 | 0,217 | |
| 7 | 152 | 1 | John Houston | USA | 51.29 | 0,194 | |
| DNS | 13 | 6 | Kieran Kelly | Ireland | DNS |
