This study of Protozoa has been carried out at three investigated sites on the Euphrates River. Samples of water and Protozoa were collected monthly for the period from April 2017 to November 2017. Some chemical and physical factors of water were studied and the results showed that the water temperature was ranged from 17 to 35 °C, Total Dissolved Solids (TDS) ranged from 400 to 779 mg.l-¹, turbidity ranged from 2-7 NTU, Magnesium (Mg2+) ranged from 50 to 299 mg .l-¹, and Chloride (Cl-2) were ranged from 100 to 203 mg.l-¹ while Sodium ranged from 44-87 mg.l-¹. Concerning the Protozoa, 25 taxa were identified which belonged to two Classes: Ciliata and Sarcodina. According to the Shanon-Weiner index, species diversity for Protozoa were ranged from 0 to 0,9 bits/individual. Jaccard’s similarity index among months showed that the highest similarity was recorded between April and June with 0.83 %