The Official Online RBS 6 Nations Store is open. The store has everything you need to get behind your team during the RBS 6 Nations, plus the store is now fully stocked with a much wider range of rugby merchandise.
Pienaar, who can also play at fly-half, made his Super 14 debut with the Sharks in 2005 and made his first appearance for South Africa in 2006.
The Magners League outfit are negotiating with his club Natal Sharks for his release, but it is thought he will link up with the Irish province in time for the start of next season.
Ulster Rugby Operations Director David Humphreys said: “Bringing Ruan to Ulster is a massive statement of our ambition to be competing with the top teams in the Magners League and Heineken Cup.”
"He is one of the most naturally gifted players in world rugby and having had huge experience at international level with the Springboks,” said Humphreys.
“We believe Ruan will help Ulster achieve success over the next couple of seasons."