The Irish province have been given special dispensation to make a short-term overseas signing after Jared Payne suffered an Achilles injury that leaves him facing a lengthy spell on the sidelines.
Terblanche 36, who made his final appearance for the Natal Sharks in their Currie Cup final defeat against the Golden Lions on Saturday, has previous experience of the RaboDirect PRO12 having played for the Ospreys earlier in his career.
Terblanche's arrival at Ravenhill will depend on how long it will take to meet the requirements of the UK Border Agency, but he will be joining some familiar faces in the form of former Sharks' team-mates Johan Muller and Ruan Pienaar as he provides cover ahead of Ulster's Heineken Cup campaign.
Ulster's director of rugby David Humphreys said in a club statement: "At this stage in the season with players all under contract it was always going to be difficult to recruit a high-calibre individual to provide cover for Jared, but we delighted that we have been able to convince Stefan not to hang up his boots just yet."
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