Upsilon Xi III was a habitable planet, the third in the Upsilon Xi star system.

In the late 2270s, the USS Enterprise stopped off at Upsilon Xi III so that the crew could enjoy shore leave on the planet. While many of the crew took the opportunity to visit the planet, Lieutenant Commander Nyota Uhura remained aboard ship. (TOS - Star Trek II Short Stories short story: "Under Twin Moons")

planets visited by the USS Enterprise (NCC-1701) (2273-2285)
Admiral Kirk's command (from 2273)	Earth • Nelestra • Zaran II • Levaeri V • Starbase 16 planet • Andrea IV • Agena IV • Mycena• Starbase 8 planet • Barak VII • Andronicus • Starbase 28 planet • Phaeton • Hephaestus • Zeta Reticuli II • Starbase 9 planet • Lieberman's World • Miaplacidus V • Valerian • Goran IV • Zenna IV • planet of telekinetic herds • Starbase 11 planet • Parides IV • Khepri • Pollox IV • Upsilon Xi III • Belle Terre • Lycos V
Spock's command (until 2285)	Earth • Thieurrull • Starbase 12 • Regula	Admiral Kirk's command (2285)	Earth • Genesis Planet • Organia • Beta Epsilon VI • Babel • Vulcan • Romulan planetoid