Rheumatoid arthritis (RA) is a chronic, inflammatory and autoimmune joint disease, leading to irreversible damage to the joint structures. The pathogenetic mechanism is not fully understood, but it is assumed that it can be caused by the interaction of genetic and surrounding factors which causes a loss of tolerance and autoimmune response to its own antigen, manifested in the development of arthritis and systemic disorders. Most important biological markers (biomarkers) are rheumatoid factor (RF), anticitrullinated protein antibodies (ACPA) and anti-carbamylated protein antibodies (Anti-CarP). Biomarkers are important for clinical and therapeutic control of all RA phases because they can help predict disease development in people at risk, improve diagnosis and provide useful prognostic information. They also help us choose adequate therapies and by using them we evaluate the response to the treatment. Symptoms such as erythrocyte sedimentation and C-reactive proteins give us information on the activity of the disease but are not a good predictive indicator. New knowledge of biological markers opens up opportunities for targeted treatment that greatly improves patient care and reduces medical expenses. Early diagnosis and timely initiation of treatment with synthetic and biological drugs are extremely important in order to prevent the irreversible consequences of this serious illness.