In recent years, commercial glyphosate herbicide formulations have been widely used in agriculture to control aquatic weeds. These pesticides may result in disruption of ecological balance, causing damage to non-target organisms including fish, diatoms and other aqutice organisms. We assessed the effect of the commercial formulation Roundup® using artificial steram , An experiment was carried out using indoor experimental channels (artificial streams) to assess the long-term effect (20 days) of pesticide on periphyton communities exposed to low levels of Glyphosate (Roundap® formulation),The herbicide was added at four doses: a Control (without Roundup) and three treatments of 20,40 and 60 mg Lˉ¹ of the active ingredient (glyphosate). The effects of Glyphosate on community biomass were assessed by measuring dry mass, ash-free dry mass (AFDM), autotrophic index (AI) and chlorophyll a factors. In artificial streams with Roundup, there was a significant (p <0.05) reduction of chlorophyll a compared to controls. Roundup produced a clear delay in periphyton colonization in treated artificial stream and values of the periphyton mass variables (dry mass, ash-free dry mass (AFDM) and chlorophyll a ) were always higher in control channel Compared channeles with low and medium herbicide concentration.