UKIP's Nathan Gill scored the Party's best ever result in a Welsh Assembly election and pushed Labour to the finish in the Ynys Mon by-election.
The seat was retained by Plaid Cymru candidate and former BBC presenter Rhun ap Iowerth with more than 42% of the vote
Nathan won 14.32 % of the vote while Labour took 15.88% with just over 300 votes between them.
The Conservatives took just 8.5% while the Lib Dems hardly registered with a paltry 1.43%.
Party Director Lisa Duffy said: "We are still developing our presence in places like Ynys Mon but this result shows how credible we are becoming right across Britain.
"UKIP received nearly twice as many votes as the Tories in this by-election and with the Lib Dems receiving just 1% of the vote, it is clear that voters here have rejected the Coalition parties.
"Our aim in Wales now is to provide some real opposition to the stagnant Labour/Plaid Cymru tit-for-tat politics and we'll go on doing just that."
The full results were: