Aim: The entomoeba coli which is an intestinal parasite is known as apatojen. However in some studies it has also been reported that it may be pathogenic. The Adenosine deaminase (ADA) is the key enzyme of purine metabolizm and controls the levels of adenosine and deoxy adenosine in the cell. The researchers have found that ADA is a marker of cellular immunity and the increased ADA serum in different diseases. In the study the comparison of ADA levels between the serums of the patients with detected Entamoeba coli (E. coli) and the control group is purposed.