This study aimed to document and analyze the traditional and ethnobotanical knowledge of the medicinal plants used in the treatment of gastrointestinal diseases. These group of diseases is  one of the most prevalent diseases in human societies and causing significant health trouble.
The data were collected over a period of two years (2017-2019) in the state of Chlef through questionnaires and interviews of the local population. In total, 74 informants from rural populations were interviewed in different regions. The surveys allowed for the collection of sociodemographic data and traditional knowledge about medicinal plants and their use to treat gastrointestinal diseases.
 The results showed that 33 plant species belonging to 22 families were widely used by the local population in the treatment of various gastrointestinal disease. Lamiaceae was the most used family (27.3%). Among all species, leaves were the most used part (50%), and decoction was the most recommended (51.4%) preparation form. In addition, stomach aches, colon problems, stomach ulcers, diarrhea, flatulence, hemorrhoids, and constipation were respectively the most treated diseases. Overall, Myrtus communis L. and Tetraclinis articulata(Vahl) Mast., were the common  species used by the local population throughout the study area.
The present study presents a baseline information on the local medicinal plants that used in the treatment of gastrointestinal disease in Chlef, Algeria, Further chemical, and pharmacological studies to validate this information are needed.