ObjectiveTo investigate evolving food retail systems in Thailand.DesignRapid assessment procedures based on qualitative research methods including interviews, focus groups discussions and site visits.SettingSeven fresh markets located in the four main regions of Thailand.SubjectsManagers, food specialists, vendors and shoppers from seven fresh markets who participated in interviews and focus group discussions.ResultsFresh markets are under economic pressure and are declining in number. They are attempting to resist the competition from supermarkets by improving convenience, food diversity, quality and safety.ConclusionsObesity has increased in Thailand at the same time as rapid growth of modern food retail formats has occurred. As fresh markets are overtaken by supermarkets there is a likely loss of fresh, healthy, affordable food for poorer Thais, and a diminution of regional culinary culture, women's jobs and social capital, with implications for the health and nutrition transition in Thailand.