This study attempts a discourse of the impact that trans-border crime could possibly have on the state of security in Mfum border area of Nigeria. A lot of the activities taking place in the Mfum border area are unlawful and as such pose serious threat to national security as well as exposing the weak state of the Nigerian security apparatus and agencies. This study gives a background of transnational organized crimes, it also identifies the state of security in Mfum border area, and it further examines trans-border crime and security in the area. Some causes and effects of trans-border crime in Mfum border are carefully analysed. The paper recommends amongst others, that government should increase the manpower of the security officials in the Mfum border area as well as ensure the prioritisation of modern technology in combating crimes across the border area.