23 September 1976
The South African government announced its decision to allow multi-racial teams to represent the country in international sporting events. Ironically, in the domestic games the segregation was still strictly imposed. More than a decade before the announcement, the country was banned in the 18th Olympic Games in Tokyo, Japan. The decision to ban South Africa was announced by the International Olympic Committee (IOC) in Switzerland. The country was given an ultimatum but failed to meet the terms.   
References

Evans Alistair Boddy, ‘This Day in African History: 23 September’, from About.com African History, [online], Available at africanhistory.about.com [Accessed: 20 September 2013]|BBC News, ‘1964: South Africa is banned from Olympics’, [online], Available at news.bbc.co.uk [Accessed: 20 September 2013]