Paternity tests are required to determine if a man claiming to be the father of a child is in fact that child's biological father, or if a man denying paternity is in fact the father. South African law acknowledges three kinds of tests to determine paternity:

Blood test

Can only exclude a man as the biological father of a child.

Analysis of white blood cells (HLA tissue typing)

Can identify the biological father to 99.9% certainty

DNA testing

Identifies the genetic 'fingerprint' unique to each person. DNA testing is the most recent type of test and the most certain.
If you would like to have a paternity test, you will need to make an appointment with a general practitioner, who will refer you to the pathology department for the necessary procedure.