A container (10) used for sterilizing medical instruments and the like has a sealed filtered vent. A wall or a lid of the container has a vent area formed by a plurality of holes (12) that pass therethrough. The vent area is surrounded by a convex ridge (16) on an outside surface of the container, with a corresponding concave recess (26) on an opposing inside surface. A web of filter material (36) is sized and adapted to cover the vent area and overlie the concave recess. A cover plate (37) is generally planar, with a vent area formed by a plurality of holes (38) that pass through the cover plate. This vent area is surrounded by a convex ridge (43) that is sized and adapted to correspond to the concave recess of the sterilization container. An elastomeric gasket (127) with outwardly-projecting ridges is secured to at least the convex ridge of the cover plate. A means for mounting the cover plate over the vent area of the container secures the filter material between the container vent area and the cover plate.
