|Location:||Denobula Triaxa system|
Classified as M class, Denobula was an inhabited planet. This was the homeworld for the Denobulans, a warp capable humanoid species. This was, also, the home of the Denobulan lemur. The planet was located in the Denobula Triaxa system. This system was located in the Alpha Quadrant.
The planet was heavily populated, with approximately twelve billion inhabitants in 2152. These inhabitants lived on a large continent. This was the only continent on this planet. (ENT: "The Catwalk") The cities were quite crowded, though Phlox noted that the atmosphere was "vibrant, communal". (ENT: "Doctor's Orders") The first Human to serve on Denobula was Doctor Jeremy Lucas, who was stationed there circa September 2151. (ENT: "Dear Doctor")
- "Fight or Flight" (referred to as homeworld)
- "Breaking the Ice" (first mention of Denobula)
- "Dear Doctor"
- "Vanishing Point"
- "The Catwalk"
- "The Crossing"
- "The Breach"
- "Doctor's Orders"
- "Cold Station 12"
- "Terra Prime"
Shortly before Star Trek: Enterprise was cancelled at the end of its fourth season, Phlox actor John Billingsley expressed an interest in viewing Denobula on the series, saying, "I would love to see a visit to Denobula."  In fact, Manny Coto once stated that, if the series had gone into a fifth season, Enterprise would indeed have visited the planet. 
According to the Star Trek: Star Charts (pp. 36, 44, "United Federation of Planets"), the Denobula Triaxa system, also known by its Bayer designation as Iota Boötis, was located in or near Federation space, in the Alpha Quadrant. Denobula Triaxa A was a G class star with a magnitude of +7, which was 1/10 the brightness of Sol. Denobula Triaxa B and C were G class stars. In the mid-22nd century, Denobula was a destination on the Earth-Denobula, Fellebia-Denobula, Neethia-Denobula, Pyrithia-Denobula, Pree'-Denobula, and Vulcan-Denobula runs. In 2378, Denobula was a Federation member.