his study applies financial portfolio theory to the energy security issues of East Asia's major energy importers: China, Japan, South Korea and Taiwan. We calculate the relative risks associated with the dynamics of oil imports, and the import prices paid, and estimate the efficient frontiers for corresponding import portfolios. Last, we run several scenarios which simulate the effects of restructuring oil import portfolios and external disruptions. We find that: The composition of oil import portfolios determines varying risk levels for given oil import growth rates and average import prices (see Figure 1), pointing to different energy security priorities for the economies studied. Increasing the share of oil imports originating from Saudi Arabia would improve the portfolio performance of China, but result in higher portfolio volatility for the other importers. The short-run impact of a fully enforced Iranian oil export embargo would increase portfolio risk across the board within a 3% to 15% range. However, the subsequent substitution of Iranian oil imports by other suppliers would prove beneficial for Japan and Taiwan. The risk premium associated with passing through the Malacca Straits, 10% of the price of the cargo, would result in a 27.5% increase in price volatility for China's oil imports. The negative impact on its average import price level, however, would be less pronounced-at 2.6% compared with a range of between 5.2% to 5.8% for the other importers.