Even though the US sends a team of superstars to the Olympics, often called the Dream Team, they are not guaranteed to win.
There are loads of non-US players in the NBA now, and they could upset the favourites, who won gold at Sydney in 2000.
Who are the British hopes for Athens?
There isn't a British basketball team at the Olympics.
Who are the big stars?
The player everyone will be looking out for is a US player called LeBron James.
He left high school (secondary school) to play professionally with the Cleveland Cavaliers and was named rookie of the year in 2004.
The player who finished second, Carmelo Anthony, will also be playing.
Another big star could be Yao Ming, a giant Chinese center who plays with the Houston Rockets in the NBA.