The olive mill wastewater (Zibar) is considered a major environmental problem due to the high toxic contents such as polyphenols.. Many of the proposed treatment processes have not been efficient in decreasing the high toxicity of Zibar to reduce the ecological impact of Zibar. Bioremediation using microorganisms might be considered an environmentally compatible and least expensive alternative. In this work, four fungal isolates were tested for their efficacy in reducing the toxicity of Zibar. Erlenmeyer flask (125 ml) containing 25 ml of Zibar were inoculated each with PDA disks (5 cm grown with the fungi). The flasks were placed on a rotary shaker at 150 rpm for two weeks. . Results of this work showed that all fungal isolates were able to grow on Zibar. However, only one isolate (OMWW2) showed significant reduction of total phenols. The concentration of phenols in the presence of isolate OMWW2 was 57.75 mg/ml compared to 159.27 mg in the control untreated water. The ibar was tested on seed gemination f tomato. The results showed 83% germination rates in the presence of treated Zibar compared to zero germination rates in nontreated Zibar%.