To assist in combating the use of explosives by terrorists. Thermedics Detection has developed an Explosives Detection System named EGIS. This system is based upon high-speed gas chromatography coupled with a highly selective and sensitive chemiluminescence detector. EGIS has been deployed in numerous applications worldwide. Examples are given of the use of EGIS as part of a layered security system for screening carry-on baggage, checked baggage, vehicles, and mobile applications.