Thailand enjoys tropical climate, a great biodiversity and long history of culture. Ancient Thai people might select edible plants from nature to fulfill their life. These plants are currently used as vegetables, spices, herbs, condiments, and sometimes as medicine. Some of these local edible plants (vegetables) are being common to other countries, however most of other useful plants have not been introduced to the rest part of the world. To date, only a limited information on local edible plants in Thailand have been published. One of the difficulties for those who study edible Thai plants is the confusion in plant identification and classification. A plant name in a regional dialect corresponds to a different plant in other dialects. And, the same plant has different local names by region. Some times local people are confused and put the same name to plural plant species. On the other hand, many of wild plant species in the world have been extinguished year by year. Some local edible plants in Thailand, especially that is not cultivated, are also being very difficult to identify nowadays. Therefore, it is necessary to record, sort out and classify local edible plants in Thailand base on certain taxonomic systems as soon as possible. Local vegetables are used not only to provide nutrition and flavor food but also to maintain health and promote wellness. For example, the chemopreventive effect of herbal diets on cancer, cardiovascular diseases and so on was revealed by numerous epidemiological studies as well as animal experiments. Collaborative research team of AVRDC-The World Vegetable Center, Kasetsart University, Japan International Research Center for Agricultural Sciences (JIRCAS) and National Food Research Institute of Japan are trying to identify chemical constituents exhibiting such chemopreventing effects in edible Thai plants. And the team is planning to develop useful products applying the function of edible Thai plants, too. We do hope these activities will contribute to improve the economical status of Thai farmers by adding new values to local agricultural products, particularly indigenous vegetables, and to provide safer and healthier food for consumers through evaluation of local vegetables.