While in Johannesburg, Mr. Clinton is also due to help celebrate the 87th birthday of former South African President Nelson Mandela.
On Monday, the former president opened a pediatric AIDS clinic in Lesotho to help its government treat children with HIV/AIDS.
The clinic will provide a supply of life-prolonging anti-retroviral medicine for sick children.
Some 20,000 children in Lesotho are infected with HIV, the virus that causes AIDS.
Mr. Clinton has also made a brief stop in Mozambique. He will later travel to Tanzania, Kenya and Rwanda.
Some information for this report provided by AFP.