The surveys taken at a large number of polling stations across the UK are traditionally released soon after the close of polling and were spot on with their predictions in the last 2010 general election.
This year's exit results suggest the Tories will get 316 MPs to Labour's 239 once all the results have been counted.
It suggests the Liberal Democrats will get 10 MPs, the Scottish National Party (SNP) 58, Northern Ireland's DUP 8, Welsh Plaid Cymru 4, UKIP 2 and the Greens 2.
The first official election result came in from Sunderland just 50 minutes after the close of polling at 2200 hours (local time) and it was a victory for Labour, which held on to its traditional stronghold.
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The exit polls have left a number of poll pundits baffled as it is not in line with the opinion polls over the last few weeks, which had suggested a far more neck and neck race between the Conservatives and Miliband-led Opposition Labour.
SNP leader Nicola Sturgeon was also cautious about the exit poll, which places her party on the course of its biggest win in Scottish history.
"I'd treat the exit poll with HUGE caution. I'm hoping for a good night but I think 58 seats is unlikely!" she tweeted.
Pollsters interviewed 22,000 people in 141 polling locations in 133 constituencies throughout Great Britain for the exit poll.
A total of 650 Westminster MPs will be elected, with about 50 million people registered to vote in an election which has reported a fairly high turnout.