The event will raise funds for the Chris Burger/Petro Jackson fund
Saracens will play the South African Barbarians at the Honourable Artillery Company, in the heart of the City of London, on Thursday, May 16.
Nigel Wray, the Saracens Chairman, said their matches at the HAC have become calendar events in the City.
"We look forward to another fantastic occasion offering great rugby and a great atmosphere in a unique venue," Wray said.
"The South African Barbarians stand for everything that is good in our game, and they will present talented, formidable opposition."
Dave Kennealy, President of South African Barbarians, said: "This match against Saracens will give young South African players a valuable opportunity to play in the UK and to showcase their ability, and the event will also generate funds for the Chris Burger/ Petro Jackson fund, supporting individuals injured while playing rugby."
Morné du Plessis, President of the Chris Burger/ Petro Jackson fund, said: "We are delighted to be associated with what will be an outstanding rugby occasion."