Six people were arrested and three police officers injured during protests about the leader of a political party appearing on a television programme.
Nick Griffin is the leader of the British National Party, which some people think has racist ideas.
Hundreds of people gathered outside BBC studios in London on Thursday as they didn't think he should be allowed on the late-night show, Question Time.
They wanted the BBC to change its mind, but the recording happened as planned.
BBC bosses said it wasn't their job to say if a politician should or shouldn't be on TV, whatever the views of their party.
Nick Griffin entered Television Centre by a back entrance to avoid protesters
They said that because the BNP won seats at the most recent European elections they had enough support to be involved in political programmes.
As well as being the leader of the BNP, Nick Griffin is a Member of the European Parliament for the party.
Many people don't think a party that's considered racist should have been given the chance to air their opinions on national television.
Question Time is one of the most well-known political programmes around.
Show bosses invite politicians and other experts to appear, and they are questioned by a studio audience about important political points and issues.
Thursday is the first time a member of the BNP has taken part in the programme.
The BNP don't let anyone who isn't white join them. A court case is taking place at the moment to decide if this policy is legal or not.
During the case Mr Griffin said he would ask the other members of the BNP to change that rule, but that vote hasn't happened yet.
The BNP also doesn't like people from other countries moving to the UK.
But the BNP insists that doesn't mean it's racist - it says it's standing up for white people who were born in Britain.