Background: An ethnobotanical field study on the traditional uses of wild plants for food as well as medicinal and veterinary plants was conducted in four Waldensian valleys (Chisone, Germanasca, Angrogna, and Pellice) in the Western Alps, Piedmont, NW Italy. Waldensians represent a religious Protestant Christian minority that originated in France and spread around 1,170 AD to the Italian side of Western Alps, where, although persecuted for centuries, approximately 20,000 believers still survive today, increasingly mixing with their Catholic neighbours. Methods: Interviews with a total of 47 elderly informants, belonging to both Waldensian and Catholic religious groups, were undertaken in ten Western Alpine villages, using standard ethnobotanical methods. Results: The uses of 85 wild and semi-domesticated food folk taxa, 96 medicinal folk taxa, and 45 veterinary folk taxa were recorded. Comparison of the collected data within the two religious communities shows that Waldensians had, or have retained, a more extensive ethnobotanical knowledge, and that approximately only half of the wild food and medicinal plants are known and used by both communities. Moreover, this convergence is greater for the wild food plant domain. Comparison of the collected data with ethnobotanical surveys conducted at the end of the 19th Century and the 1980s in one of studied valleys (Germanasca) shows that the majority of the plants recorded in the present study are used in the same or similar ways as they were decades ago. Idiosyncratic plant uses among Waldensians included both archaic uses, such as the fern Botrychium lunaria for skin problems, as well as uses that may be the result of local adaptions of Central and Northern European customs, including Veronica allionii and V. officinalis as recreational teas and Cetraria islandica in infusions to treat coughs. Conclusions: The great resilience of plant knowledge among Waldensians may be the result of the long isolation and history of marginalisation that this group has faced during the last few centuries, although their ethnobotany present trans-national elements. Cross-cultural and ethno-historical approaches in ethnobotany may offer crucial data for understanding the trajectory of change of plant knowledge across time and space. Keywords: Ethnobotany, Wild food plants, Medicinal plants, Alps, Italy