Abstract : Rheumatoid arthritis (RA) is a systemic, inflammatory, autoimmune disorder characterized by predominant synovial proliferation, bone destruction and degradation of articular. Adenosine deaminase, referred to as ADA (adenosine aminohydrolase, EC 3.5.4.4) is an important deaminating enzyme which converts adenosine and 2 –deoxy adenosine to inosine (III) and 2-deoxy inosine, respectively suggesting that ADA is a key enzyme in the purine A set of membrane-bound enzymes expressed in immune cells regulates these substances dynamically during inflammation [8]. Therefore, interest has arisen for the possible role of this enzyme in the emergence of this disease, In the human body, trace elements play a variety of roles, Amongst them, Mg is essentials in several pathway. The study involves 60 female RA patients and 60 healthy females in the control group, all participauts age between 25 and 65. When RA patients were compared to healthy individuals, the obtained data have revealed a statistically significant elevation in ADA level in patients when compared to controls (P<0.05) and while insignificant difference has been noticed between Mg levels in patients in comparison with healthy subjects (p>0.05). In the current study the levels of ADA have been evaluated in sera of rheumatoid arthritis, their magnesium concentration has been measured as well. There have been much interest in the measurement of ADA levels in a number of disturbances as its deficiency or overproduction is greatly associated with serious health problems including tuberculosis, diabetes and rheumatoid.