How many olympic medals did Michael Johnson win?

4.

Michael won gold in 400 meter dash at the 1996 games in Atlanta and 2000 Games in Sydney, 200 meter dash at the 1996 Games, and 4x400 meter relay at the 1992 Games in Barcelona.

He won a fifth gold medal, in 4x400 meter relay at the 2000 Games, but was stripped of the gold when two of his teammates tested positive for performance enhancing substances.