ABSTRACT. – Macroinvertebrate assemblages in Kebi-Rhumel, one of the largest watersheds in Algeria, are insufficiently documented. During spring, summer and autumn 2018, macro-benthos and water samples were collected and treated out at 16 stations located in the main confluence area along the Kebir-Rhumel wadi. One of the main objectives of the present work was to investigate diversity and distribution of benthic macroinvertebrates species according to environmental characteristics in this catchment area. The pH, conductivity, dissolved oxygen, ammonia, nitrite and phosphate were significantly different (P value < 0.05) between the sampling sites. The conductivity and nutrient concentrations were higher in the upstream part of the Kebir-Rhumel catchment, while dissolved oxygen decreased, indicating that Rhumel wadi is more polluted. A total of 16,069 individuals and 129 taxa, belonging to 77 families in 15 orders, were identified. Mean values of taxon richness, Shannon-Wiener (1949), Pielou’s (1966) evenness, Margalef (1958) and Simpson (1949) indices indicate that Kebir wadi and their tributaries supported a more macro-benthos diversity than Rhumel wadi. The species composition and the EPT index (Ephemeroptera, Plecoptera, Trichoptera) showed the occurrence of pollution-sensitive macro-benthos groups in Kebir wadi, while the Rhumel wadi was mainly characterized by pollution-tolerant taxa, indicating anthropogenic disturbance and habitat degradation, which is evident by the diagnosis of the physicochemical water quality at Kebir-Rhumel wadi. Canonical correspondence analysis (CCA) revealed that altitude, conductivity, dissolved oxygen and nitrate were found to be the primary factors affecting the communities structure of benthic macroinvertebrates in the study area.