Lichens are rather special living creatures belonging to the cryptogam phylum. In fact, a lichen is an original being resulting from a symbiosis between an alga and a fungus. The aim of our work is to carry out an inventory of the Ouled Brahim region (Saida). To do this, we used the [4] method, which consists of applying a transparent 20x50 cm survey grid to the bark of trees, starting one metre above the ground. This grid is cut into 10 cm2 squares. We collected 8 charts, four for each station (Mimouna and AinKsab). A total of two lichen genera were identified, presented by 4 different species.