His dream is to compete in Beijing this summer.
Today the I.A.A.F., the International Track Organization, ruled against him. The I.A.A.F. found the high-tech, carbon fiber prosthetics Pistorious uses are an advantage. They allow him to run faster without working as hard as he would have to on two legs.
Robert Hersh of the I.A.A.F. said, "We don't want to be in a situation where somebody could develop a prosthetic that would give a clear advantage."
Pistorius dismisses that, and says he has a responsibility.
"On behalf of myself and other disabled athletes, to stand firmly and not allow one organization to inhibit our ability to compete using the very tools without which we could not walk, let alone run" said Oscar Pistorius.
He began running in 2004 after a rugby injury.
"I train hard, I eat and sleep well" said Pistorius.
By 2006 he had shattered Paralympic records and began to compete against able-bodied athletes.
Last year he finished 2nd in the 400-meter race at the South African Nationals. His dream is to finish first in Beijing.
Oscar Pistorius' manager says he will appeal the decision ruled today. He has called the whole idea of an advantage "pure discrimination."