The main aim of this study was to identify, catalogue and document the large number of wild medicinal plants used in the M'Sila region (northern Algeria) for the treatment of several human pathologies. Another more ambitious aim is to contribute to overcoming the limits of an orally transmitted pharmacopoeia, attempting to exploit the large ethnopharmacology patrimony of the region for further pharmacological purposes. Our field study was carried out over a period of three years (2008–2010). During this period, herbalists were interviewed using semi-structured questionnaires investigating the herbalist as a holder of information (gender, age and educational level) and about wild medicinal plants (local name, uses and part used). In addition, the relative importance value of the species was determined and informant consensus factor (ICF) was calculated for the medicinal plants included in the study. A total of 83 herbalists were interviewed; men dominate the practice of traditional medicine in the region. About 41% of them are between 31 and 40 years, and about a third (34%) are illiterate. The traditional herbal knowledge is passed from generation to generation in the verbal form, a writing tradition being almost totally absent. The interviewed herbalists identified and recorded 58 plants species and 50 genera belonging to 27 plant families. Lamiaceae and Asteraceae were the most represented plant families. The aerial parts were the most commonly used plant part, while infusion and decoction were the most common method of traditional drug preparation. The survey provides a veritable source of information on the herbalists and wild medicinal plants. Plants which are used in different parts of the world for the treatment of similar diseases may be deemed to be effective in pharmacological terms. These medicinal plants may be incorporated into the healthcare delivery system of the country. Display omitted