Illness had prevented Epainette Mbeki from travelling to Pretoria to receive the Order of the Baobab on Thursday, said the Chancellor of the National Orders, Frank Chikane.
Mbeki, who lives in the Eastern Cape, was to have been conferred with the honour by her son, President Thabo Mbeki, for her "exceptional contribution to the economic upliftment of underprivileged communities in the Eastern Cape and her commitment to the fight against apartheid".
"Alternative arrangements will be made to confer the honour on her," Chikane said.
The Order of the Baobab, the Order of Luthuli, the Order of the Companions of O R Tambo and the Order of Mapungubwe are the highest awards the country can make.
"This is the seventh time that our free people have had occasion to salute in humble gratitude such distinguished men and women who are indeed the stars on our national firmament," Mbeki said at a ceremony at the Union Buildings.
"Today, they are admitted into the ranks of those who belong to the national orders of our republic. Because of their efforts, we are able to live and develop in a world of freedom, without the fetters of oppression or exclusion."
Mbeki conferred the Order of the Baobab on Grace Masuku, for her contribution to environmental conservation, Mamohau Ntsoane, for community upliftment and social welfare, and Ivan Toms, for helping in the struggle against apartheid and sexual discrimination.
The Black Sash's Sheena Duncan received the order for her part in the struggle for a non-sexist, just and democratic South Africa, Wolfram Kistner was honoured for fighting for justice, equality and democracy, and Lindiwe Myeza for the economic upliftment of women and underprivileged communities.
University of South Africa Principal Barney Pityana received the order for his part in creating a just and democratic South Africa and spiritually uplifting the oppressed.
The Order of Luthuli was made posthumously to Fort Calata, Sicelo Mhlauli, Sparrow Mkhondo, Ruth First, Joe Nzingo Gqabi, Ama Naidoo, John Tengo Jabavu, Pixley Seme and Amina Pahad.
They were acknowledged to have served the country's interests by making a meaningful contribution in the struggle for democracy, human rights, nation-building, justice and peace and conflict resolution. The order was also conferred on Isaac Lesiba Maphotho and Constitutional Court Judge Albie Sachs.
The sole recipient of the Order of Mapungubwe was George Ellis, recognised for his scientific achievements.
Sotiris Mousouris of Greece received the Order of the Companions of O R Tambo for his mark on local journalism and for fighting for the ideals of freedom and justice.
The order was conferred posthumously on King Moshoeshoe II of Lesotho and King Sobhuza II of Swaziland for their "exceptional contributions to the struggle against apartheid through supporting the liberation movement in times of need".
Also posthumously honoured with the order were Botswana's former president Sir Seretse Khama, for his "exceptional contribution to the struggle against apartheid through supporting the liberation movement in times of need, and contributing to the development of the African continent", and former president of Mali Modiba Keita. - Sapa