Sickbay, also known as the medbay, was the main medical center aboard Federation starships. The section was presided over by the chief medical officer (CMO), a senior staff member. The CMO was supported by various medical practitioners. The area was also used for certain analyses of new lifeforms a starship might encounter, and for developing treatments for unknown diseases or illnesses. When rendering aid to a stricken planet or spacecraft, the sickbay staff treated and cared for the wounded. On starbases, sickbay was typically called the infirmary.

Sickbays were well stocked with a variety of medical equipment and supplies. Much of it was left out on tables or benches for use by the medical crew, but some items were stored in cargo crates. On 24th century starships, if a piece of equipment was needed but not available it could be replicated.

Three or four biobeds generally lined the walls of sickbay's intensive care unit, or ICU; these were for patients receiving medical care and were equipped with biofunction monitors. The room also had surgical beds, where major surgeries were performed, and critical patients were treated.

Sickbays typically had small laboratory facilities attached to the ICU. The chief medical officer or other associated personnel could monitor experiments or run tests here during their duty shift. The laboratory was equipped with a full bioisolation field. Many starships also have separate, larger medlabs. Galaxy-class ships had at least four.

The chief medical officer's office was also located in or near sickbay.

The Emergency Medical Holographic program was an asset to medical personnel introduced in 2370. It could be activated in the event of a major emergency or loss of the medical staff. Although its value was indisputable, many Starfleet doctors, including Beverly Crusher, were not fond of the program, and it was rewritten several times.