A steam autoclave (steam sterilization system) has a door for opening and closing an opening that defines the entrance to and exit from a steam sterilization chamber. The door may be latched and locked and pneumatically sealed when in a closed position. Preferably, the door has a convex portion that projects into the sterilization chamber when the door is in a closed position for aiding in providing an even distribution of steam throughout the sterilization chamber during operation of the steam autoclave.