Sars said the discovery was made on Wednesday, just four days after customs officials blocked two bags containing 10 horn weighing 24.96kg from leaving the country via the same airport.
In Wednesday's incident, customs officials followed up on news of a suspicious bag on a plane bound for Hong Kong.
One of the plane's passengers, whose nationality Sars did not specify, was identified as the owner of the bag which was put through a scanner.
Sars said a physical inspection found the contents to be mould in the shape of five rhino horns concealed in one to two centimetres of hard wax wrapped in paper.
The passenger and the goods were handed over to the South African Police Service for further investigation.
In a separate incident, customs officials intercepted consignments destined for Hong Kong with a selection of counterfeit designer label goods weighing 1.2 kg's valued at R1.4 million at a cargo shed at OR Tambo International.
The goods included belts, jackets, shirts and sneakers which were handed over to the police for further investigation.
African News Agency