East Asia has experienced a rapid mortality decline in recent history. Its life expectancy at birth has increased by about 30 years in the last half century. This paper analyses data collected from Hong Kong, Japan, Korea, Mainland China, and Taiwan. It provides a systematic examination of long-term mortality trends, their age patterns and sex differentials. While mortality transitions in these populations took place in different times and under different political systems, levels of socio-economic development and living environment, changes in their age patterns of and sex differentials in mortality have shown certain regularities. Through decomposing changes in life expectancy by age and major causes of deaths, the paper also sheds light on the relationship between epidemiological transition, changing age patterns of mortality and improving life expectancy in these populations.