Background: Northern Thailand is the home of many ethnic groups who possess great knowledge of ethnomedicine, so it is the location with the highest number of ethnobotanical studies in Thailand. However, the Pwo have never been included in. Therefore, this study is the first ethnobotanical study of Pwo people. Methods: In this study, 50 Pwo informants from 8 villages in Omkoi district were interviewed about their ethnomedicinal knowledge. They were asked about the vernacular name(s) and uses of plant species found in their villages and nearby forests. Results : A total of 122 ethnomedicinal species with 930 use-reports were recorded. Leaves were the most preferred plant part and decoction was the most preferred preparation method. Herbs were the most favored life form of ethnomedicinal plants used by Pwo people. Asteraceae, Fabaceae, and Zingiberaceae were the three most dominant plant families, which contributed 22% of the total species. Most plants with high Use value (UV) values were common species which also found and reported in other ethnobotanical studies however, the exception was Garcinia pedunculata Roxb. ex Buch.-Ham. Although only a single individual was found in nearby forests, but it was commonly used by Pwo people in the studied sites. The five ailments with high recorded IAR included: injuries, muscular-skeletal system, pain, respiratory systems, and digestive systems. These ailments were directly related to the life-style of Pwo people. Conclusion : The comparison between the species found in this study and a study of Sgaw Karen in a nearby area showed that their knowledge differed from each other in both species and their uses despite their close proximity. The results emphasize the importance and the need of ethnobotanical studies although in the areas where many studied have been carried out. The more understanding of the traditional knowledge would increase our chance of understanding and identification of medicinal properties of plants. The results would lead to the discovery and development of new pharmaceutical substances to improve human life quality.