Dinaal (or Dinaali) was an inhabited planet and the homeworld of the Dinaali people, located in the Delta Quadrant. Dinaal was very densely populated, and almost every part of the planet was filled with high-rise buildings constructed with no regard for aesthetics. The over-building and over-population had poisoned the atmosphere of Dinaal and had led to ecological disasters and famine.
Due to the over-industrialization, the Dinaali could not effectively provide medical care to their population. To combat this, the Dinaali asked the Jye, renown administrators, to reform their health care system. The Jye introduced the Allocator a complex global computer system, which considered the profession, skills, and accomplishments of each person in order to determine his or her treatment coefficient or "TC". All citizens on Dinaal, as well as visitors, were given a TC.
The Dinaal employed enormous hospital ships, also rigidly administered by the Jye, to service the medical needs of each metropolis. The hospital ships had four levels which were prioritized according to the TC of the patients in that level. The highest, and consequently wealthiest, level was level blue, while the lowest was level green. The lower down the scale patients were, the lower the quality of care they received. The ships also contained a fifth level, level white, which acted as a morgue.
One side effect of the Jye administration was a blind bureaucracy. Patients in the lower levels might be allowed treatment for one affliction but not another, or denied medication that was plentiful in higher levels. The Dinaal had learned to accept the system as a necessity for their large society. (VOY: "Critical Care")
According to the Star Trek: Star Charts (p. 79), Dinaal was the fourth planet in the Dinaal system. This M-class world was governed by the Dinaali Corporate from the planetary capital of Dinaal City. The planet was shared between the humanoid Dinaali, Jye, and Dralian. In 2378, there were 18.7 billion individuals living on this planet. The Jye and other species have provided medical and technological aid to this heavily polluted planet.
According to the Star Trek: Star Charts (p. 94), the Dinaal system was a binary system with two G-class stars. The USS Voyager visited this system on stardate 54170.