How did he do in Athens?
Michael Phelps didn't win eight gold medals in Athens as planned, although returning home to the US with six gold medals is pretty good going.
He also picked up a couple of bronze medals too to end up with eight. Not bad for a 19-year-old.
What Newsround said before the Games
If swimmer Michael Phelps achieves his aim for the Athens Games he will go down in history as one of the finest Olympians of all time.
Phelps, 19, will swim in eight events at the Olympics, and should he win all of them he would break the record of Mark Spitz, who won seven golds at the 1976 Olympics.
At the 2003 world championships, Phelps took home six medals and broke five world records.
His performances made him the only person to ever break five individual world records at one international event.
In 2004 he has won five US national titles and goes to Athens as world record holder in the 200m butterfly, 200m individual medley and 400m individual medley.