Adenosine deaminase (ADA)plays an important role in the regulation of normal immune system.The altered activ-ity of serum ADA could associate with some autoimmune diseases(AID).Various studies abroad have found the elevated ac-tivity of serum ADA compared with healthy controls in many kinds of AID such as systemic lupus erythematosus (SLE), rheumatoid arthritis(RA),et al (P<0.05).Many studies foused on the correlation of altered activity of serum ADA with the disease severity,but there is still controversy.To explore the diagnostic value of serum ADA in AID,make a review a-bout the application research progress of ADA in several AID.