Deck 4 is dedicated completely to medical facilities and other departments relating to crew and patient care. The cornerstone of the medical department is Sickbay, located in the forward section of deck 4. Most primary medical care takes place in the confines of sickbay.

Sickbay is designated as one of the ship's primary emergency shelters, and several surrounding compartments in the medical complex are also used during catastrophic emergencies aboardship.