The female calf named Belle was born at the zoo on the 27th October, 2019.
The scimitar-horned oryx is one of the most-threatened antelopes in the world, but Belle's birth brings the total count to three calves born at Marwell in 2019 alone.
The species was assessed as 'extinct-in-the-wild' in 2000 by the IUCN Red List of Threatened Species and only exists today, after being bred in captivity.
Marwell Wildlife, which owns and runs Marwell Zoo, has been vital in preserving the rare species.
Marwell Wildlife’s Conservation Biologist, Tania Gilbert, said:
“The scimitar-horned oryx was one of the first species we brought to Marwell Zoo when we opened in 1972.
"Since then we’ve had an incredible 366 calves born here, making them one of our biggest success stories, both in terms of breeding and conservation success.
“Our scimitar-horned oryx have been transported as far as Canada, Japan, Australia and New Zealand, but most importantly we’ve reintroduced groups of oryx into protected areas in Tunisia to re-establish them in their natural habitat.
"We continue to research the re-established populations and work to enhance the biodiversity of the protected areas where they live.”
The oryx were reintroduced to Tunisia in 1985, with the animal arriving from Marwell and Edinburgh Zoo.
In 1999 and 2007, Marwell co-ordinated further released into three more protected areas.
Today, there are around 220 across five protected areas.
Marwell Wildlife are monitoring the species across Tunisia's protected area network.