The precise objective of the current study was to document the ethnobotanical knowledge on antidiarrhoeal plant-use by lay people in a rural community in Eastern Himalayan region of Arunachal Pradesh, India. Data was collected from 60 randomly selected indigenous households in three communities using semi-structured questionnaires. In total, 34 species of plants belonging to 31 genera in 16 families were reported to be used in the preparation of the herbal remedies for the treatment of diarrheoa in the study area. Eleven species of plants, namely, Averrhoa carambola, Citrus limon, C. medica, Clerodendron venosum, Manihot esculenta, Mikania scandens, Oxalis triangularis, O. corniculata, Piper betle, Sonchus wightianus and Swertia hookerii, were documented for the first time for their use in the treatment of diarrheoa. Herbal remedies were commonly used by people for the treatment of diarrheoa because of its cost-effectivity. The result of this study provides the basis for further pharmacological studies on the herbal remedies used. The wide variety of plants that are used to treat diarrhoea supports the traditional value that medicinal plants have in the primary health care system of the rural people in eastern Himalayan zone of Arunachal Pradesh.