Biomarkers are indicators of biological conditions that can be detected and 
measured in body fluids or tissues. Biomarkers can be detectable before the 
clinical onset of the disease, and are thus useful for prognosis; they can be 
measured at early stages of the disease and are useful for stratification and 
classification of the disease and patients; they can be monitored along the 
disease course and used as indicators of risk factors and pharmacological 
response to treatment. Ideally, biomarkers should be sensitive, specific, have 
high predictive power, and be easily accessible. Rheumatoid arthritis (RA) is 
the most frequent chronic inflammatory disorder, affecting millions of people 
worldwide and leading to joint damage and substantial morbidity. RA is a 
heterogeneous disorder with a fluctuating clinical course and unpredictable 
prognosis. And although a large panel of biologics is available to clinicians, 
the main challenge remains to treat patients as early as possible with the most 
personalised therapy. Today, the most challenging issue in RA is the 
identification of biomarkers for early disease diagnosis and for prediction of 
drug response. Among molecules that can fulfil this expectation, micro(mi)-RNAs 
certainly represent an option. The potential value of miRNAs as a novel class of 
biomarkers is well documented in cancer. Moreover, the presence and stability of 
miRNAs in body fluids provide fingerprints that can serve as molecular 
biomarkers for disease diagnosis and therapeutic outcome. As a growing body of 
evidences reveals abnormal expression of specific miRNAs in RA tissues, the use 
of a blood-based miRNA signature for optimal diagnosis and treatment becomes a 
realistic option.