The debate over the justification of regime switch on 2005 which involves the abandonment of fixed exchange rate regime in Malaysia has yet to be resolved. Thus, a series of econometric methods were proposed in this study to examine the suitability of the exchange rate regime which is implementing in the context of Malaysia and ASEAN countries. The findings from the study supported the theory of Optimum Currency Area. This book has proposed a sequence of empirical methodology provided guideline for policy maker on how to make a decision on determining a suitable exchange rate regime in a nation.