The SA Communist Party congratulated the ANC on Tuesday on its 101st anniversary and urged the party to remain humble.
"The SACP wishes to say to our ally... the ANC must strive to remain a humble servant of the poor and to radically change their lives for the better," said spokesman Malesela Maleka.
He said over the years the ANC had led the struggle for liberation with humility, which had won the hearts of ordinary people.
"It is for this reason that our people have continued to entrust the ANC with a mandate to govern our country."
The ANC's anniversary celebrations will be hosted in Durban, where its leaders and those of its alliance partners - the SACP and the Congress of SA Trade Unions - would visit various communities, and the house of former ANC president John Langalibalele Dube.
Maleka said the ANC had to prioritise the people's needs and address unemployment, poverty and growing inequalities.
The ANC Youth League has also wished the party a happy birthday.
Spokeswoman Khusela Sangoni-Khawe said the ANC had, since its inception, spearheaded the struggle for political, social and economic change.
"2013 provides, therefore, yet another opportunity to advance and consolidate this struggle for urgent, decisive and radical action to change the people's lives for the better and this is our birthday wish for all South Africans...," she said.
Sangoni-Khawe said the ANCYL's task was to mobilise the youth behind the ANC's vision and to champion youth interests within the party.
She said it should celebrate its birthday by creating a democratic society characterised by accessible and quality education, and in which youth unemployment was treated as a national emergency.