were randomly selected in six stratified age groups (Table 1). In each village, all medicinal plant species data obtained from a key informant who resides in that village were prepared for the semi-structured interview. During the interview, plant pictures and the Karen plant names were shown to the informant. The questions were asked individually concerning their actual medicinal use together with questions about what plant part was used, mode of preparation, and route of administration. The semi-structured interviews were conducted in Thai in the presence of a translator when the informants could not communicate in Thai.