Terblanche played in 37 tests for South Africa, scoring 19 tries, including a South African test record of four tries (equalled with Chester Williams and Pieter Rossouw) on debut against Ireland at Bloemfontein on 13 June 1998, which he later bettered by scoring a then record five tries against Italy on 19 June 1999.
Terblanche started his career under the tutelage of Nick Mallet at the Boland Cavaliers (66 caps). He made his debut in 1999 for the Natal Sharks and played for the Ospreys in Wales. Terblanche moved back to the Natal Sharks for the 2007 Currie Cup season in South Africa. He played his return game for the Durban-based franchise at Fullback and scored two tries and claimed man of the match in the Shark's 32–16 defeat over Western Province, the team who has won the Currie Cup title a record 32 times. This was also his 100th match played for the Sharks.
He is known as a great finisher—his test try per match ratio of 0.51 is among the highest in Springbok history and is significantly better than those of players like Carel du Plessis (0.33), Breyton Paulse (0.4) and Jean de Villiers (0.4), on par with current stars Jaque Fourie (0.5), Bryan Habana (0.57)[contradiction] and old legend Pieter Rossouw (0.48) but short of Ray Mordt (0.66 or two tries in every three tests), and Danie Gerber's (0.79) incredible scoring records. On 3 October 2007 it was announced that Terblanche had re-signed for the Natal Sharks on a one year contract. In 2010, Terblanche was appointed captain of the Natal Sharks.
On 1 November 2011 he signed a 3 month contract with Ulster rugby to provide cover for Jared Payne who ruptured his achilles in the PRO12 match against Treviso on 7 October.