Hospital bed mattress covers provide outer protection to a mattress by preventing blood and other fluids from entering the inside (inner core) of the mattress. Covers may be coated with, or contain an antimicrobial solution that kills germs (viruses or bacteria), or prevents bacterial growth.

There are multiple terms used to describe hospital bed mattress covers: water-resistant (keeps liquid away from the material), water-proof (prevents liquid from entering inside the material), or water-repellent (keeps liquid away from the material and prevents liquid from entering inside the material). Covers are usually detachable from the mattress or the mattress lining, meaning that they can be removed or replaced.