Polling in all 18 Northern constituencies began at 7 o clock this morning and continues until 10 o clock tonight.
Almost 1.2 million electors are registered and entitled to vote at 624 polling stations across Northern Ireland.
After polling, the 1,512 ballot boxes will be taken to eight count centres where, for the first time, counting will begin immediately.
According to the electoral office in Belfast, it is hoped that all 18 constituencies will declare before 3 o clock on Friday morning, subject to recounts.
Votes cast in West Tyrone and in Fermanagh South Tyrone will be counted in Omagh. Sinn Feins Pat Doherty is a clear favourite in West Tyrone.
While the Fermanagh South Tyrone contest promises to be close between Sinn Feins Michelle Gidernew, who currently holds the seat, and Independent Unionist Rodney Connor, he's the only Unionist in the constituency standing for election. Former UTV presenter, Fergal McKinney also stands for the SDLP in Fermanagh South Tyrone.
In Derry the Foyle constituency is being defended by former SDLP leader Mark Durkan, his closest rival is expected to be Sinn Feins, Martina Anderson. Journalist and campaigner, Eamon McCann also runs in Foyle.
In East Derry, sitting MP Gregory Campbell of the DUP is fighting the TUV’s William Ross.