The evolution and grow of international trade has made the ta sk assi gned to cus to ms services more important and com-plex. No w day’s custo ms adm inistration i s a relevant regulatory operator in international trade as facilitator and accele-rator of trade. However, the study of efficiency on the public sector is more co mple x tha n t he st ud y of e ffi cie ncy i n t he private, profit-oriented sector; due to the fact that public sector efficiency can be defined as capacity to achieve goals instead of perceiving profits. T he aim of this research is to identify those areas which yield the greatest cost/efficiency gains from the implementatio n of the e-service s ystem Inte rnational Trade Sin gle Window (ITSW) and to note the ob-stacles or disadvantages present on the implementation of the ITSW in Mexico as a case of study. The findings point out tha t, acc ordi ng to the first result of t he implementation of the IT SW, Mexico has made good progress related to the effic iency of i nternational trade procedures, simplifying the flow of information between traders and customs adminis-tratio n and r educing t he time i n customs clearance in 20