DNA mismatch repair (MMR) genes of MLH1, MSH2, MSH6 and PMS2 play essential roles in maintaining microsatellite stability through DNA mismatch repair, pathogenic variation in MMR genes causes microsatellite instability and high cancer risk as represented by the Lynch syndrome. We identified 17,687 MMR variants from 18,844 ethnic Chinese individuals. We characterized the basic biological features of MMR variation and determined MMR pathogenic prevalence of 0.17% in the general Chinese population. Our study provides a comprehensive view of MMR variation in human population, a resource for study of human MMR variation, and a reference for MMR-related cancer applications. (By Dr. San Ming Wang, https://jmg.bmj.com/content/early/2021/06/25/jmedgenet-2021-107886 )