Aim of the study: : The survey aims to study the effect of geographic separation of ethnic groups on local knowledge of medicinal plants used by Akha people in Thailand and China, who were separated 100-120 years ago, to see how different the two geographically distinct but culturally similar groups were in this respect. Materials and methods: : Interviewing 10 villagers in each of five Akha villages, three in Thailand and two in China, about which plants they used and how they used them. Results: : A total of 95 medicinal plants registered in the five villages only 16 were shared between China and Thailand. Otherwise the use patterns were quite similar with respect to which plant families and plant growth forms were used and also in terms of in which habitats the Akha found their medicinal plants. Conclusions: : The moving to a different site has forced the Akha to find a new set of species, but that when using these new species they have maintained other traditions relating to medicinal plants. © 2008 Elsevier Ireland Ltd. All rights reserved.