6 September 1989
Frederik Willem de Klerk was elected State President of South Africa and was officially inaugurated on 20 September. De Klerk had been Acting State President since 15 August 1989, following the resignation of President P.W. Botha on 14 August. His announcement on 02 February, 1990 to release Nelson Mandela and unban the African National Congress (ANC), Pan Africanist Congress (PAC), the South African Communist Party (SACP) and other liberation movements was received with mixed feelings in-and outside Parliament. On 17 March, 1992, De Klerk succeeded in gaining the support of the White electorate in the referendum which, as he put it "closed the book on apartheid" and paved the way to a new dispensation for all the people of South Africa. He served in this position until the first democratic elections were held in 1994.
References

Centre for Conflict Resolution at Salisbury University, ‘Frederik Willem de Klerk: Leadership and Making a Difference’, [online], available at www.conflict-resolution.org (Accessed: 13 September 2013)|

South Africana History Online, ‘Frederik Willem de Klerk’, [online], available at www.sahistory.org.za [Accessed: 23 August 2013]|

O’Malley, P. ‘1989’, from Nelson Mandela Centre of Memory, [online], available at www.nelsonmandela.org.za [Accessed: 23 August 2013]|

South African History Online, ‘F.W. De Klerk is inaugurated’, [online], available at www.sahsitory.org.za [Accessed: 23 August 2013]