Scottish election: UK Independence Party profile
British withdrawal from the EU was the UK Independence Party's original raison d'etre when it was formed by Alan Sked in 1993, not long after the Maastricht Treaty was signed.
Mr Sked, a history professor at the London School of Economics, believed the EU was corrupt and anti-democratic, and a danger to the British economy.
From the outset UKIP was torn by internal divisions, and the leader resigned in the wake of the 1997 election after arguing the party should refuse seats on the European Parliament "gravy train".
There was also an acrimonious split involving accusations of right-wing extremism, with Mr Sked saying UKIP was "doomed to remain on the political fringes".
But it made gains in the 1999 European election under the leadership of millionaire businessman Michael Holmes, winning its first three seats and 7% of the vote.
This success, however, was followed by more in-fighting and the party was on its fourth leader in 2004, when it won 16% of the vote in the European elections and returned 12 MEPs.
UKIP's anti-EU policy seemed to have struck a chord with the electorate, with the party beating the Liberal Democrats into fourth place.
After the election, UKIP's star candidate, TV presenter and former Labour MP Robert Kilroy-Silk, attracted media attention by openly jockeying for the leadership. But he quit after failing to wrest control from Roger Knapman, a former Conservative MP.
Despite some gains in local elections, and the Euro result boosting its public profile, UKIP failed to make a breakthrough in the 2005 general election, losing deposits in more than 450 seats, costing the party about £225,000.
When current leader, Nigel Farage, took over the helm in 2006 he tried to move UKIP away from its public perception as a single-issue pressure group, and widen its appeal.
Its vote held up in the 2009 European elections and the party increased its MEPs to 13.
In the general election the following year it won just over 3% of the vote and took no seats. On the morning of polling day, Mr Farage was injured when his light aircraft crashed in Northamptonshire.
The party has had no electoral impact in Scotland, polling less than 1% of the vote in successive elections.
It is standing 36 candidates in every region and launched its manifesto with a proposal to scrap MSPs and "replace" them with Scottish Westminster MPs.
Other pledges include a halt on all overseas aid, banning new wind farms, restricting immigration, restoring grants for UK university students, repealing the Human Rights Act and the smoking ban.