The first incident, involving a bus and a small vehicle occurred in the northern province of Limpopo at 2am local time, killing eleven people.
Later in the day, a mini bus laden with commuters, collided with a truck, south of the port city of Durban.
"We have learnt that 14 people died on the scene after a taxi driver lost control of his vehicle and crashed onto an oncoming truck," said Sipho Khumalo, an official at the Kwazulu Natal department of transport.
The privately operated vehicles are notorious for speeding, poor maintenance and overloading of passengers.
A week ago, 29 commuters were killed when a bus crashed into a lorry, north east of the capital Pretoria.
Despite its sophisticated road networks, South Africa battles a high rate of road fatalities, with about 38 fatalities on average per day, according to government figures.