After the war, the US made a list of the most important Iraqis they wanted - Uday and Qusay were second and third on that list after their father.
On Wednesday, the US military revealed it had also picked up the person who is number 11 on the list
Both US and UK troops have been attacked in recent weeks by Iraqi people who still support the old leadership.
If those Iraqis see that such important people have been killed, they may be less likely to attack US and UK soldiers in the future.
People in Iraq started celebrating when they heard about Saddam's sons being killed.
Gunshots were fired all over Baghdad to mark the news.
The man who tipped off the US military about where the brothers were hiding is set to receive a £18.7 million reward.
He's said to be under US protection since the deaths.
British Prime Minister Tony Blair said it was a "great day for the new Iraq".
But it's still not known where Saddam Hussein himself is.