The medicinal plant Peganum harmala L, known locally as harmal, belongs to the Zygophyllaceae family, native from North Africa to India. In Algeria, it is one of the plants most widely used by the local population as an alternative remedy for daily care and to treat various ailments. This first ethnobotanical survey of the traditional knowledge and uses of P. harmala was carried out in five communes in the province of Sidi-Bel-Abbès, in western Algeria, between 2021 and 2022, involving 250 informants (160women, 90men).The most commonly used parts of the plant are the seeds and leaves, but infusion, decoction, steam-cooking and fixed oil are the most common methods of preparation. The diseases most frequently treated were digestive problems, followed by urinary infections, genital problems and osteoarticular diseases, etc. The surveys carried out provided important information on the therapeutic use of the plant by the local population, as well as assessing their knowledge of the plant's toxicity and the recipes used by informants to reduce toxicity with a view to safer use, particularly by vulnerable groups such as pregnant and breast-feeding women, who use a new method of preparation (steaming) inherited from their grandmothers, which they believe to be safe.