This paper aims to apply the comprehensive regional economic integration index for the Southern Common Market (Mercosur) and the Pacific Alliance, which are the most prominent economic integrations in Latin America and the Caribbean. By using the thirteen variables in the four dimensions, and by calculating the weights from the Principal Component Analysis methodology, it reports the composite index for each dimension and the overall regional economic integration index. In case of the output and input market, the degree of integration is higher in Mercosur than in the Pacific Alliance, while the results are reversed in the financial and foreign exchange market. Unlike the previous three markets, both economic integrations have the similar degree of integration in the Global Value Chain. Finally, Mercosur is more comprehensively integrated than the Pacific Alliance, while recently, the effects of integration has been reduced in the output market.