An election to the 56th Parliament of the United Kingdom for the constituency area of Merthyr Tydfil and Rhymney, held as part of the general election on 7 May 2015.
Labour hold by Gerald Jones with a majority of 11,513 - 35.2% - on a turnout of 53.0%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| JONES, Gerald | Lab | 17,619 | 53.9% | 10.2% |
| ROWLANDS, David | UKIP | 6,106 | 18.7% | 15.9% |
| REES, Bill | Con | 3,292 | 10.1% | 2.5% |
| MANN, Rhayna | PC | 3,099 | 9.5% | 4.4% |
| GRIFFIN, Bob | LD | 1,351 | 4.1% | -26.9% |
| PARRIS, Elspeth | Green | 603 | 1.8% | - |
| BLANCHE, Eddy | Ind | 459 | 1.4% | - |
| GRIFFITHS, Robert | Comm | 186 | 0.6% | - |
Under section 13(b) of the Representation of the People Act 1985, a candidate gaining 5% or less of the vote share will forfeit their deposit.
An electorate of 61,716, having a valid vote count of 32,715 and an invalid vote count of 95.
Result declared at 03:11 on 8 May 2015.