A system for containing medical waste with an opening for sterilization, of those commonly used for the heating and sterilization inside an oven, that comprises a container with a lid, and a mechanism for opening and closing the lid of the container; the container having a threaded upper edge; the lid being provided with a rubber seal that makes the container airtight, the opening and closing mechanism of the lid of the container having opening and closing capability in accordance with the heat experienced inside the oven, characterized in that it also comprises a double-layered bag housed inside the container and a central inner shaft located in an axial position and arrangement and a spring that runs the length of, and concentric to, said central inner shaft and arranged on the downward side of the lid oriented towards the container, with a pushing piece on the free end of the spring and the central inner shaft being insertable in the bag; and the bag being made up of two sub-bags (31, 32), one of which is housed inside the other, both sub-bags (31, 32) being sealed at the lateral contours thereof at the opening thereof, an inner sub-bag being made of LDPE heat shrink material and the other outer sub-bag made of high-density polyethylene (HDPE) material; wherein the opening and closing mechanism of the lid of the container comprises: two holes in the upper region of the wall of the container, and a stop on the periphery of the container on the upper region and adjacent to the upper threaded edge of the container; two lower latches-openings and two circular latches on the lid, the two lower latches-openings being diametrically opposite and fixed to the lid, and the other two circular latches also diametrically opposite and fixed to the lid at a higher position in relation to the two latches-openings and both pairs of elements separated by an angle approximately 20 degrees from a plan view of the lid; two metal rods (11a, 11b) in a vertical arrangement, arranged diametrically opposite on the wall of the container and contiguous, on their upper end, to the holes of the container and secured and fastened at the lower end thereof on the inner vertical wall of the lower region of the container, and said metal rods (11a, 11b) having the greater part of the longitudinal extension thereof separated and without making contact with said inner vertical wall of the container, the metal rods (11a,11b) also being provided with protrusions on the upper end thereof of suitable dimensions for the passage thereof through the contiguous hole of the wall of the container, the metal rods (11a, 11b) being also provided with a suitable flexibility to move close to the inner vertical wall of the container when they are subjected to the necessary force, where the protrusions pass through the respective hole and connects to the latches when the metal rods (11a,11b) are close to the inner vertical wall of the container. two holes in the upper region of the wall of the container, and a stop on the periphery of the container on the upper region and adjacent to the upper threaded edge of the container; two lower latches-openings and two circular latches on the lid, the two lower latches-openings being diametrically opposite and fixed to the lid, and the other two circular latches also diametrically opposite and fixed to the lid at a higher position in relation to the two latches-openings and both pairs of elements separated by an angle approximately 20 degrees from a plan view of the lid; two metal rods (11a, 11b) in a vertical arrangement, arranged diametrically opposite on the wall of the container and contiguous, on their upper end, to the holes of the container and secured and fastened at the lower end thereof on the inner vertical wall of the lower region of the container, and said metal rods (11a, 11b) having the greater part of the longitudinal extension thereof separated and without making contact with said inner vertical wall of the container, the metal rods (11a,11b) also being provided with protrusions on the upper end thereof of suitable dimensions for the passage thereof through the contiguous hole of the wall of the container, the metal rods (11a, 11b) being also provided with a suitable flexibility to move close to the inner vertical wall of the container when they are subjected to the necessary force, where the protrusions pass through the respective hole and connects to the latches when the metal rods (11a,11b) are close to the inner vertical wall of the container.