The present study investigates the possibility of growing microalgae in wastewater generated from olive oil production factory. Wastewater samples were collected from the three stages of olive oil production as well as from the final effluent of the factory. The analysis results of the effluent revealed that it contains: nitrogen (0.31%), phosphorus (0.59%), potassium (0.70%), calcium (741ppm), iron (59.78 ppm), magnesium (301 ppm), cupper (5.45 ppm), sulfur (314 ppm) and high amount of phenolic compounds (2999.4 mg /L). Nostoc muscorum, Anabaena oryzae and Spirulina platensis were chosen as three blue-green microalgae and were cultivated in standard media and two media from olive oil industry effluents. The three microalgae were cultivated over 30 days period on olive effluent (OWW) and diluted effluent (OWW 50%). The growth of the three strains in diluted media OWW50% showed better results as expressed from the total chlorophyll, optical density and biomass dry weight. The total chlorophyll content values of Spirulina, Anabaena and Nostoc genera were 2.3, 1.87 and 1.87µg/L, respectively. Dry weights obtained in diluted OWW50% were 1.72, 1.45 and 1.28g/L for Spirulina, Anabaena and Nostoc, respectively. The values of optical density were 0.38 for Spirulina, 0.29 for Anabena and 0.25 in case of Nostoc. During algae cultivation, the initial phenols concentration was reduced by 50-60% in 15 days, and more than 80% of phenols were removed by day 30. Thus blue-green microalgae could be grown on olive oil wastewater for biomass production and wastewater treatment of phenolic compounds.