Purpose of Review Health efects of long-term exposure to ambient PM2.5 vary with regions, and 75% of the deaths attributable to PM2.5 were estimated in Asia-Pacifc in 2017. This systematic review aims to summarize the existing evidence from cohort studies on health efects of long-term exposure to ambient PM2.5 in Asia-Pacifc. Recent Findings In Asia-Pacifc, 60 cohort studies were conducted in Australia, Mainland China, Hong Kong, Taiwan, and South Korea. They consistently supported associations of long-term exposure to PM2.5 with increased all-cause/nonaccidental and cardiovascular mortality as well as with incidence of cardiovascular diseases, type 2 diabetes mellitus, kidney diseases, and chronic obstructive pulmonary disease. Evidence for other health efects was limited. Inequalities were identifed in PM2.5-health associations. Summary To optimize air pollution control and public health prevention, further studies need to assess the health efects of long-term PM2.5 exposure in understudied regions, the health efects of long-term PM2.5 exposure on mortality and risk of type 2 diabetes mellitus, renal diseases, dementia and lung cancer, and inequalities in PM2.5-health associations. Study design, especially exposure assessment methods, should be improved.