This is an ethnobotanical study focused on the traditional medicinal plants used by local communities to treat human diseases. It was carried out from March to September 2020, in Righa dahra forest in the wilaya of Setif, Algeria. This forest is located in a bioclimatic transition zone with vegetation stages from the thermo Mediterranean to the supra Mediterranean, which contribute to develop a very important floristic richness. The research was based on a data that collected using semistructured interviews, group discussions and questions asked to the population of this region; experienced elderly people, men and women ... about herbal remedies and how to use them in traditional medicine. Descriptive statistical analysis of 100 interviews were identified a total of 58 medicinal plants, distributed in 30 families plant. The result showed that grass constituted the highest proportion of medicinal plants (55%) followed by shrubs from which it was found that Artemisia herba-alba and Juniperus phoenicea are the most useful species by the population of this region. Plants families with the highest medicinal plants in the study area used for various diseases treatment were Lamiaceae, Apiaceae and Cupressaceae. Leaves (27%) were the most frequently utilized plant parts for preparation of traditional herbal medicines. Oil was a widely used mode of preparation of traditional remedies followed by infusion. It appears that most plants are used in the treatment of 30 condition bellings to seven diseases groups of which gastrointestinal diseases and respiratory diseases are the most treated by plants.