Abstract: An ultraviolet sterilization and decontamination system which is particularly useful in ultraviolet passthrough applications. The system includes a shell having a reflective inner surface and a barrier positioned within the shell and spaced inwardly of the inner surface of the shell, the barrier being formed of a material which will transmit at least about 70% of the desired wavelength of ultraviolet light. The space between the shell and the barrier defines a lamp cell for holding one or more ultraviolet lamps and the interior of the barrier defines a sterilization cell wherein items can be sterilized or decontaminated. The barrier is supported within the shell by supports and reflective endwalls substantially seal the lamp cell from the sterilization cell, as well as substantially sealing the sterilization cell and lamp cell from communication with the external environment.