This thesis examines the link between the traditional medical knowledge and medicinal plant use in Atiu, Cook Islands. Indigenous knowledge systems and medicinal plant populations have been reported to be under threat from international organisations, social and natural scientists alike. An interdisciplinary perspective using anthropological and ethnobotanical methods was used to empirically assess the effect of healing practices on ethnomédical knowledge transmission and medicinal plant conservation. This study shows that despite socioeconomic changes and the decline of traditional practices in general, traditional medicine in the Cook Islands continues to be used across social and geographical boundaries without posing a threat to medicinal plant populations. This effect is attributed to the adaptive properties of the healing system that maintains some traditional elements such as family ownership of medical recipes and absence of monetary reward for healing while allowing for innovation as demonstrated in new recipes for new illnesses and flexible knowledge transmission patterns. The family ownership of medicinal recipes facilitated the conservation of both ethnomédical knowledge and medicinal plants as specific families operated as custodians of specialised knowledge and associated plant populations. The sense of obligation to the community's wellbeing and divine guidance that accompanied the practice of traditional medicine contributed to the operation of a moral and spiritual driving force behind this form of cultural and biological preservation. In short this study shows that engagement with traditional medicine is positively associated with the transmission of ethnomédical knowledge and the conservation of medicinal plants, as Atiuans strive to conserve medicinal plants in order to acquire the elevated social status associated with traditional healing. These findings contribute to the ethnobotanical literature on the conservation of biocultural diversity by highlighting the impact of knowledge transmission on plant management.