An election to the 56th Parliament of the United Kingdom for the constituency area of Lagan Valley, held as part of the general election on 7 May 2015.
DUP hold by Jeffrey Donaldson with a majority of 13,000 - 32.7% - on a turnout of 55.9%.
Candidates
| Name | Party | Vote | Vote share | Vote change |
| DONALDSON, Jeffrey | DUP | 19,055 | 47.9% | -1.9% |
| REDPATH, Alexander | UUP | 6,055 | 15.2% | - |
| LUNN, Trevor | APNI | 5,544 | 13.9% | 2.5% |
| CATNEY, Pat | SDLP | 2,500 | 6.3% | 1.3% |
| LOVE, Alan | UKIP | 2,200 | 5.5% | - |
| MORRISON, Samuel | TUV | 1,887 | 4.7% | -3.9% |
| MCGEOUGH, Jacqui | SF | 1,144 | 2.9% | -1.1% |
| ORR, Jonny | Ind | 756 | 1.9% | - |
| OSBORNE, Helen | Con | 654 | 1.6% | - |
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 71,152, having a valid vote count of 39,795 and an invalid vote count of 191.
Result declared at 01:21 on 8 May 2015.