A single use, hermetically sealing mousetrap has a housing defining an enclosure that contains a killing mechanism which is accessible through a rotatably mounted door controlled by a spring-loaded door opening gear mechanism. Mounted to the bottom of the housing inside the enclosure is a spring-actuated setting axle and setting bar combination that is movable between a tripped position and a set position by manipulation of a setting handle positioned outside the enclosure. When the setting axle is moved to the set position, the door opening gear mechanism causes the door to open while tensioning a torsional door spring. A trip latch and bait pedal are configured to operate together to secure the setting bar in the set position, with subsequent movement of the bait pedal by a mouse serving to release the trip latch. When the trap is thereby triggered, the setting bar moves to the tripped position where it both activates the killing mechanism and releases the door opening gear mechanism. The tensioned door spring then closes the door and the killing mechanism kills the mouse. With the door closed, the enclosure is hermetically sealed with the dead mouse inside and the trap can be disposed of without any contact between the user and the carcass along with any parasites and pathogens associated therewith.