The use of medicinal plants in Morocco has a long history and plays an important role in health care of the Moroccan population. This study is one of the first ethnobotanical studies that compare the ethnomedicinal knowledge of two types of expert informants on medicinal and aromatic plants conducted in contrasted regions of Morocco. It documented medicinal plant uses in three provinces (Meknes, Fez and Taounate) using semi-structured interviews. Overall,85 herbalists and 78 cooperative directors shared their knowledge of 151 plant species belonging to 64 families. This study revealed a rich diversity of medicinal plants in the three studied provinces, with a remarkable distinction in knowledge between herbalists and cooperative directors. Concerning the species used, the Asteraceae (16spp.), Lamiaceae (14spp.), Apiaceae (13spp.) and Fabaceae (10spp.) were the dominant families. Origanum compactum Benth was the most cited species (95%). Respiratory system diseases were the most frequent targets of the medicinal plants used (Informant agreement ratio= 0.95), whereas musculoskeletal system disorders were the lowest (0.81). This study can help identify those medicinal plants with the highest importance and utilization in these provinces. This information can hopefully be of interest to both future researchers, for pharmacological testing and conservation, and policy makers to better improve the medicinal plant research and assist those working in this sector.