Oscar Leonard Carl Pistorius was born to Henke and Sheila Pistorius on 22 November 1986 in Sandton, Johannesburg, in what was then Transvaal Province (now Gauteng Province) of South Africa. He grew up in a Christian home and has an elder brother, Carl, and a younger sister, Aimee. Pistorius credits his mother, who died at the age of 43 when Pistorius was 15 years old, as a major influence in his life. Pistorius is a white South African with Italian ancestry from his maternal great-grandfather, who was an Italian emigrant to Kenya.

Pistorius competed in T44 (single below-knee amputees) events though he is actually classified in T43 (double below knee amputee). Sometimes referred to as the "Blade Runner" and "the fastest man on no legs", Pistorius took part in the 2004 Summer Paralympics in Athens and came third overall in the T44 (one leg amputated below the knee) 100-metre event. Despite falling in the preliminary round for the 200 metres, he qualified for the final. He went on to win the final in a world record time of 21.97 seconds, beating a pair of American runners both possessing a single amputation, Marlon Shirley and Brian Frasure.  In 2005, Pistorius finished sixth in the non-disabled South African Championships over 400 metres with a world-record time of 47.34 seconds, and at the Paralympic World Cup in the same year, he won gold in the 100 metres and 200 metres, beating his previous 200-metre world record. At the 2006 IPC Athletics World Championships, Pistorius won gold in the 100-, 200- and 400-metre events, breaking the world record over 200 metres. On 17 March 2007, he set a disability sports world record for the 400 metres (46.56 seconds) at the South African Senior Athletics Championships in Durban; and at the Nedbank Championships for the Physically Disabled held in Johannesburg in April 2007, he became the world record holder of the 100- and 200-metre events with times of 10.91 and 21.58 seconds respectively.  Pistorius was invited by the IAAF to take part in what would have been his first international non-disabled event, the 400-metre race at the IAAF Grand Prix in Helsinki, Finland, in July 2005. He was unable to attend, however, because of school commitments. On 13 July 2007, Pistorius ran in the 400-metre race at Rome's Golden Gala and finished second in run B with a time of 46.90 seconds, behind Stefano Braciola who ran 46.72 seconds. This was a warm-up for his appearance at the 400 metres at the Norwich Union British Grand Prix at the Don Valley Stadium in Sheffield on 15 July 2007. As American Olympic champion Jeremy Wariner stumbled at the start of the race and stopped running, Pistorius took seventh place in a field of eight in wet conditions with a time of 47.65 seconds. However, he was later disqualified for running outside his lane. The race was won by American Angelo Taylor with a time of 45.25 seconds. Pistorius had ambitions of competing in other non-disabled events. In particular, he had set his sights on competing at the 2008 Summer Olympics in Beijing, China, but was ultimately not selected by the South African Olympic Committee (see below).

Did Pistorius retire?