Pretorius made his international debut for the Springboks on 8 June 2002 at fly-half against Wales at the Free State Stadium in Bloemfontein.
He earned a further three caps for the Springboks that year in November against Northern Hemisphere sides, playing matches against France, England and Scotland, all of which South Africa lost.
He returned to international duties in July 2003 as a reserve in the 52–16 loss against the All Blacks during the 2003 Tri Nations Series.
He played at fly-half in the subsequent matches and earned another international cap in November in the 34–23 win over Argentina in Buenos Aires.
[1] In 2007, he returned to the national side and became Jake White's 2nd-choice fly-half to Butch James, playing an extensive reserve role in the 2007 Rugby World Cup, coming on as a replacement in the final which South Africa won 15–6 against England.