Pistorius finished second in his heat in 45.44 seconds, the New York Times reported, running in front of a full 80,000-seat stadium.
"I know Oscar was the protagonist in the race, but I love him," said Luguelin Santos, the Dominican runner who won the heat against Pistorius, the Associated Press reported.
"I've worked for six years to get my chance," Pistorius told the Associated Press. "I found myself smiling in the starting block, which is very rare in the 400 meters."
The South African had both legs amputated below the knee before he was a year old, after being born without fibulas, ESPN reported, and began running competitively after he injured his knee in a rugby game.
The 25-year-old athlete's participation in the Games has stirred up admiration, but also controversy. Some believe that his J-shaped carbon-fiber “Cheetah” Flex-Foot prosthetic legs give him an unfair advantage against the competition.
“Ultimately, I’m a performance athlete,” Pistorius, who went to court to fight a ruling that his legs gave him a boost, told the Boston Globe. “I want to be respected for what I do. That respect can’t come out of finding efficiency from a piece of equipment. It must come from training hard and making sacrifices.”
World champion runner Kirani James respects Pistorius for just that, according to the Associated Press.
"My hat's off to him, just coming out here and competing," James said. "I just see him as another athlete, another competitor. What's more important is I see him as another person. He's someone I admire and respect."
"Pistorius is the greatest feel-good story of the Games," wrote ESPN's Jim Caple. "Watching him soar around the track is inspiring."