The study aims to evaluate the operational efficiency of Al-Khadraa' wastewater treatment plant and the compatibility of the quality of treated water with the Iraqi standards for disposal into rivers and valleys. The study showed that there are large variations in the quantities and quality of the influent to the plant which sometimes lead to stop operational units of the plant and this has an adverse effect upon the plant function. The results showed that the strength of the influent is classified as weak to medium. The average BOD5/COD ratio is equals to 0.6. Also it seemed that the efficiency of the treatment was weak and the quality of the effluent is out of the Iraqi standards for disposal into rivers and valleys. The percentage removal of BOD, COD, TSS, PO4, NH3 were 83.15%, 79%, 69.7%,56.15%,41.88% respectively. The sequence of removal efficiency was in the order of: NH3<PO4< TSS< COD< BOD.