An ethnobotanical study on aromatic and medicinal plants was conducted in Masmouda district (Moroccan Northwest). It was performed as a contribution to emphasize four Moroccan aromatic and medicinal species : Clinopodium nepeta (L.) Kuntze called Mantha, Lavandula multifida L. called Hlihla or lakhzama, Mentha pulegium L. called Fliyou and Centaurium erythreae Rafn called Gasat elhaya. Ethnobotanical survey was carried out on the spot during two seasons (January and March) using a questionnaire filled by herb-sellers, traditional healers and users. Our work focused on gathering all information related to therapeutic practices done by Masmouda local population about these four medicinal species. Results showed that knowledgeable people regarding virtues of these plants are composed of 76% of women and 24% of men. The study also revealed that people without income (64%) as well as illiterate people (72%) do have a strong link with traditional medicine. Decoction is the main mode of preparation for Clinopodium nepeta (L.) Kuntze, Lavandula multifida L. and Mentha pulegium L. while powder aspect is generally used for Centaurium erythraea Rafn. Leaves and flowers of these plants are the most used organs in traditional phytotherapy. By the way, Centaurium erythreae Rafn is especially intended to treat skin diseases, Mentha pulegium L. to treat respiratory diseases while lavandula multifida L. is devoted to digestive diseases and Clinopodium nepeta (L.) Kuntze is particularly used against respiratory and gastric diseases. Results of this study constitute a precious source of information for the study area. They could be a data basis for further researches in the field of phytochemistry and pharmacology with in order to find new natural substances designed as phytomedicine.