A Champions League quarter-final between AC Milan and Inter Milan had to be abandoned after the crowd started throwing flares onto the pitch.
It's not the only trouble that has marked football recently - two Newcastle United players had a fight on the pitch during a game and were both sent off.
We want to know what you think should be done to clean up football both on and off the pitch.
Do you think that if the players were better behaved the fans would be too?
Maybe you think there should be harsher punishments if there is trouble?
E-mail and let us know.
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
I don't think it should be cleaned up at all. I think it is ok apart from all the racism. I think they should sort that out first.
Jay, 14, Scotland
If the fans are misbehaving, the team shouldn't take the blame unless they are setting a bad example. If a fan is misbehaving they should be banned from watching football again. A player should have an even worse punishment as they are role models to young people and are also letting down the country.
David, 13, Cardiff
I think it's generally the fans that cause the problems. I think we need to make sure that anyone who causes trouble can be located and when people buy tickets they have to submit their details.
Clare, 13, Woking
As some of you may know, flares are very common in Serie A (Italian league) and to be honest they brighten up the stadium. However the flares shouldn't be allowed to be thrown. This is obviously the rule but nobody listens, so they should put up those metal "gates" to protect the pitch from flying objects.
Meem, 13, Camb
Inter Milan should be banned from playing in Europe for 4 years and play all there home games next season with none of there supporters in the stadium.
Bradley, 10, Lifton
My Uncle was at the tragic Heisler incident. English teams were banned from European competitions for five years. I think after that incident last night with Inter and AC Milan, Italian teams should be banned from European competitions for at least five years!
Jonathan, 12, Liverpool
I think Inter Milan should have a 2 match ban and that all fans misbehaving should be banned from going to a football match all season.
Louis, 11, France
I think that both clubs should receive heavy fines and that Inter Milan should be banned for playing in the tournament for two years.
Richard, 13, North Berwick
I think Inter Milan should be banned from Europe next season, and their matches should be played with no crowd.
Sophie, 13, Lincoln
Inter Milan players and managers should not be blamed for what happened. You could see why the fans were so angry about all the decisions that went against them. Their games should be played behind closed doors and not aired on TV so the fans suffer not the club.
Rosie, 15, Didcot
I think that they should put up some sort of protector so that rubbish can not be thrown on the pitch!
Jobhan, 13, Birmingham
There should be harsher punishments for people responsible for trouble because it not only affects the game, but it also ruins it for other people who have paid to enjoy the match. I think that there should be security checks when you come into the stadium to see what you are carrying.
Annabel, 13, Hemel Hempstead
I don't think that the team should be banned from Champions League football, it should be the fans that should.
Nick, 11, Saffron Walden
They should have more security and searches of the fans before matches. They should also tell the players to behave themselves as well.
Emily, 14, Oxfordshire
Any team who does anything like that should get punished. It's really disgusting.
Sabeeta, 13, Bradford
I think Inter should get punished by not being aloud into the European Cup next year, a fine and a public apology.
Kyle, 11, Dunfermline
I think Inter Milan's fans should be banned going to the stadium for at least 10 games. Also they should be banned from the champions league for at least 2 years. They have made the beautiful game shocking, just like Dyer and Bowyer. I'm a Newcastle fan and it's disgraceful.
Adam, 11, Dunston-Gateshead
What happened to the security at that match?! Why were people allowed to come to a football match with flares in the first place??!! Something has to be done with the security at football matches, because people getting injured on the pitch is not good.
Kate, 14, Aylesbury
I think what lee bowyer and Keiron Dyer did on the pitch is unbelievable if they have problems then they should sort it out in their own time not on a football pitch.
Hannah, 12, Birmingham
The only thing I have to say is, "Why were flares allowed on the field?" I've seen fights between players many times, and the fans do get a little protective, but they never attacked the players. They just attacked each other. Guards should check peoples' pockets before they can come in.
Ashley, 14, Alaska
Inter Milan should be banned for the next season and fined £1 million.
Josh, 13, Tonbridge
Last night was a "one-off" but surely the police officers could have prevented this from happening? - Checking on turnstiles and when they started throwing the flames they could have ran up and got the people.
Kelly, 15, Liverpool
I think that they should put a glass fence all away round the pitch like in hockey games and put them all away up.
Becky, 13, Newport
I think that only carton or cup drinks should be allowed so that it doesn't hurt the players as much if they are thrown on and to sort out fighting between players I think they should take anger management lessons. I hope something doesn't happen like this in the FA Cup Semi Finals.
David, 13, Darlington
I think that in order to keep football teams under control there should be cameras in order to make sure that fans behave. However if this continues then the team who's fans are misbehaving constantly should be banned from playing football.
Afsana, 12, Bolton
I think all the Italian clubs should be banned from European football next season.
Rebecca, 14, Essex
I think Inter Milan should be banned from playing in Europe next season. Then their fans will learn.
Josh, 13, Glasgow