Mzima, a 19-year-old eastern bongo, was the second oldest bongo in the world, The Atlanta Journal-Constitution reports.
Dennis Kelly, Zoo Atlanta president and CEO, said Mzima received the best treatment possible during her life.
"The fact that she was the oldest bongo in North America is a testament to the excellent care she received throughout her life," Kelly said Tuesday.
The University of Georgia's College of Veterinary Medicine will perform a necropsy or animal autopsy on Mzima.
Eastern bongos are among Zoo Atlanta's most endangered mammals with fewer than 500 believed to live in the wild.