An election to the 56th Parliament of the United Kingdom for the constituency area of Islwyn, held as part of the general election on 7 May 2015.
Labour hold by Chris Evans with a majority of 10,404 - 29.4% - on a turnout of 63.6%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| EVANS, Chris | Lab / Co-op | 17,336 | 49.0% | -0.2% |
| SMYTH, Joe | UKIP | 6,932 | 19.6% | 16.9% |
| JONES, Laura | Con | 5,366 | 15.2% | 1.2% |
| ACKERMAN, Lyn | PC | 3,794 | 10.7% | -2.3% |
| D'CRUZ, Brendan | LD | 950 | 2.7% | -7.7% |
| VARLEY, Peter | Green | 659 | 1.9% | - |
| BARON, von Magpie | MRLP | 213 | 0.6% | - |
| RAWCLIFFE, Josh | TUSC | 151 | 0.4% | - |
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 55,697, having a valid vote count of 35,401 and an invalid vote count of 46.
Result declared at 02:30 on 8 May 2015.