The governing African National Congress is ahead as ballot count continues in an election that has seen a low turnout.
The ruling African National Congress held a comfortable lead in South Africa's presidential and parliamentary election with more than two-thirds of the vote counted on Thursday, but the incomplete count showed the party received less support than in the last balloting five years ago.
Opposition parties made widespread allegations of corruption against the ANC a major part of their campaigns ahead of Wednesday's election.
Voter apathy appeared to have affected turnout, which fell to 65 percent from 74 percent in 2014.
The ANC, led by President Cyril Ramaphosa, had 57 percent of the vote with 67 percent of polling districts counted, according to results announced by the electoral commission.
It received 62 percent of the total vote five years ago.
The Democratic Alliance received 22 percent of the vote so far, the most of any opposition party, about the same share it received in 2014.
DA party leader Mmusi Maimane campaigned vigorously on the corruption issue. Speaking at the electoral commission's results center on Thursday evening, he said his party appeals to South Africans of all races.
"We will never be a party for whites. We will never be a party for blacks," said Maimane.
"We are a party for all South Africans."
The populist, left-wing Economic Freedom Fighters, which also made graft a main campaign issue, increased its share of the vote to nearly 10 percent support.
More than 40 smaller parties also took part in the election.
In South Africa, the president and parliament are not elected directly. The number of votes won by each party determines how many representatives are sent to the national 400-seat legislature. The president of the country is the leader of the party that gets the most votes.
Results from South Africa's more remote areas are expected to trickle in, and electoral officials say final results may not be announced until Saturday.