This paper empirically examines how closely East Asian economies move together in response to world, regional and country shocks, with a view to gauging the feasibility of a regional currency union. Unlike previous studies, a block vector autoregression (VAR) model is employed to analyze a large set of macroeconomic variables for 10 major countries in the region. Results suggest that regional GDP shocks play a pivotal role in accounting for the variation in individual countries’ GDP. Also, the majority of the GDPs in East Asia exhibit similar responses to the two major determinants of regional and world GDP shocks. Overall, the evidence presents positively for consideration of a regional currency union in East Asia. For comparison, we also estimate the degree of business cycle synchronization between Eurozone countries over the period prior to the launch of the euro in 1999.