West Midlands MEP Bill Etheridge has quit UKIP, saying it is seen by voters as a "vehicle of hate towards Muslims and the Gay community".
In a letter of resignation to party leader Gerard Batten, Mr Etheridge said UKIP had been "changed beyond all recognition".
He continued, "While there is a place for extreme nationalist and reactionary views in politics and I defend the right of you and others to hold and express your opinions, I do not believe these were the opinions and policies that UKIP MEPs were elected to represent."
His decision follows the announcement last week by MEP William Dartmouth that he was leaving the party, saying Mr Batten was taking it "further and further to the right".
Mr Etheridge said he made the decision with "great sadness" and said he expected Mr Batten would "lash out publicly" against him.
Mr Etheridge said he would continue to sit in the European Parliament as a member of the EFDD group led by former party leader Nigel Farage.
Pary leader Gerard Batten said: "I hope that Mr Etheridge will do the decent and honourable thing and resign his seat, thereby handing it back to UKIP to which it morally belongs.
"I am sure the loss of his salary, daily allowance, and pension rights would be a small price to pay for a man of principle such as he.
"It was a great pity that Mr Etheridge was unable to make it to the UKIP Conference in Birmingham last month where he could have witnessed the party members fully behind my leadership – the people who put him in the seat he currently holds by dint of their efforts and donations."