Notional results for a UK general election on 5 May 2005 Wales - Elections won by Labour
Figures presented for Labour include those candidates certified by both the Labour and the Co-operative parties.
| Constituency | Electorate | Turnout | Votes | Vote share | Majority |
| Aberavon | 50,685 | 59.4% | 18,077 | 60.0% | 13,937 |
| Aberconwy | 43,976 | 62.0% | 8,994 | 33.0% | 1,070 |
| Alyn and Deeside | 59,441 | 59.7% | 17,331 | 48.8% | 8,378 |
| Arfon | 42,998 | 58.2% | 8,484 | 33.9% | 456 |
| Bridgend | 57,046 | 59.7% | 14,621 | 42.9% | 6,089 |
| Caerphilly | 64,120 | 56.5% | 20,082 | 55.4% | 13,517 |
| Cardiff North | 64,390 | 70.4% | 17,707 | 39.0% | 1,146 |
| Cardiff South and Penarth | 67,855 | 58.2% | 18,402 | 46.6% | 8,955 |
| Cardiff West | 64,587 | 58.2% | 16,859 | 44.9% | 8,361 |
| Carmarthen West and South Pembrokeshire | 57,143 | 67.3% | 14,090 | 36.7% | 2,043 |
| Clwyd South | 51,201 | 61.2% | 14,172 | 45.2% | 6,220 |
| Cynon Valley | 48,272 | 60.2% | 18,329 | 63.0% | 14,390 |
| Delyn | 53,383 | 63.7% | 15,540 | 45.7% | 6,644 |
| Gower | 60,432 | 65.4% | 16,786 | 42.5% | 6,703 |
| Islwyn | 56,225 | 60.2% | 21,795 | 64.3% | 17,582 |
| Llanelli | 55,280 | 63.9% | 16,592 | 46.9% | 7,234 |
| Merthyr Tydfil and Rhymney | 54,044 | 55.5% | 18,129 | 60.5% | 13,934 |
| Neath | 57,278 | 62.5% | 18,835 | 52.6% | 12,710 |
| Newport East | 54,941 | 57.9% | 14,389 | 45.2% | 6,838 |
| Newport West | 60,303 | 59.3% | 16,021 | 44.8% | 5,458 |
| Ogmore | 53,842 | 59.5% | 19,542 | 61.0% | 14,839 |
| Pontypridd | 54,122 | 63.2% | 18,534 | 54.2% | 11,694 |
| Rhondda | 50,461 | 61.7% | 21,198 | 68.1% | 16,242 |
| Swansea East | 57,502 | 53.6% | 17,457 | 56.6% | 11,249 |
| Swansea West | 58,363 | 56.7% | 13,833 | 41.8% | 4,269 |
| Torfaen | 60,665 | 59.3% | 20,472 | 56.9% | 14,791 |
| Vale of Clwyd | 49,637 | 65.8% | 14,977 | 45.9% | 4,629 |
| Vale of Glamorgan | 68,229 | 68.5% | 19,068 | 40.8% | 1,574 |
| Wrexham | 48,016 | 63.3% | 13,993 | 46.1% | 6,819 |
| Ynys Môn | 52,512 | 67.5% | 12,278 | 34.6% | 1,242 |
Turnout as calculated by the House of Commons Library, is the total number of votes cast and not spoiled, divided by the size of the electorate.
Estimates of the 2005 general election result in new constituencies
Colin Rallings and Michael Thrasher, then at the University of Plymouth, produced estimates of the 2005 general election result as if the new constituencies recommended by the separate Parliamentary Boundary Commissions for England, Wales and Northern Ireland had then been in existence.
The Elections Centre, established by Professors Colin Rallings and Michael Thrasher, moved to the University of Exeter in 2003.