The present paper shows the evolution of the different exchange systems that have been presented in the countries of the G3, analyzing the potentiality of the agreement like an exercise econometrics through the co-movements exposed by Barro et. al. (2002). Test of Cointegracion o f J o h a n s e n a n d B r e i t u n g a r e performance to validate or not the implicit hypothesis of deepening in the integration process between the three countries as well as relationships of long term and of balance. Later, a model of vectorial Autorregresivos is estimated (VAR) with the purpose of identifying the behavior of the real exchange rates before an external crash.