Styris IV was the inhabited fourth planet in the Styris planetary system. In 2364, Styris IV was a Federation world.
In 2364, a rare vaccine from Ligon II was needed to combat an outbreak of Anchilles fever on Styris IV. USS Enterprise-D was tasked with treaty negotiations to acquire the medicine. During the delay in obtaining the vaccine, Starbase 14 informed the Enterprise of the infection rates and projected deaths on the planet. (TNG: "Code of Honor")