The aims of this study were to determine the physical-chemical and microbiologicalcharacteristics of olive oil mill wastewater (OMWW) resulting from the extraction of olive oil inAlgerian Sahara in Ghardaia region, and to evaluate the antibacterial activity of the OMWWextracts manifested by their phenolic compounds on the identified bacteria. This is the first studyof physicochemical and microbiological characterization of the olive mill wastewater resulting fromthe modern industrial unit of trituration of olives by three-phases centrifugation in Ghardaia re-gion in Algerian Sahara. The results showed that this effluent is too rich in organic matter thatis expressed by BOD5 and COD. It is also characterized by an acidic pH (4.8) and a high level ofphenolic compounds. The microbiological study of the olive oil mill wastewater showed the isola-tion of three GRAM positive bacterial strains (Staphylococcus aureus, Staphylococcus epidermidisand Bacillus subtilis ) and five fungal strains (Penicillium sp, Aspergillus ochraceus, Aspergillus fu-migatus, Penicillium chrysogenum and Aspergillus niger ), and one strain of yeast Saccharomycescerevisiae. The results of the antibacterial activity showed that strains which were isolated fromthe olive oil mill wastewater were resistant to the phenolic compounds whereas clinical strains weresensitive.