Abstract: A disposable medical waste bag having layers of polyethylene film has an open top and a seal at the bottom of the bag. The bag is filled to a desired level with medical waste and is sealed by closing off the top of the bag by twisting. After the top of the bag has been twisted and a twist is formed, the twist is bent over on itself and an adhesive tape located at a location on the outside of the bag is used to tape the twist to itself, thereby thoroughly sealing the bag. A normally-closed valve is provided on the bag and is removably engagable with a coupler that is used in conjunction with the hose of a central vacuum system of a medical facility such as a hospital. After the bag has been sealed such as by taping, the central vacuum system vacuums or sucks out excess air sealed within the bag thereby substantially decreasing the size of the bag. The seal located at the bottom are sealed bars of thermosealable polymer material having a plurality of triangular air pockets extending between the bars.