The aim of the publication prepared by the panel formed by the State Consultant for Rheumatology is to summarize knowledge on diagnosis and treatment of rheumatoid arthritis. Except diagnosing rheumatoid arthritis on the basis of ACR criteria, diagnostic criteria for early rheumatoid and early unclassified arthritis have been proposed. These criteria establish the usefulness of anticitruline antibody determinations, ultrasonography of joints and magnetic resonance. The most important procedure in early detection is to establish the presence and activity of inflammatory process, based on history, physical examination, laboratory tests and, possibly, ultrasonography and magnetic resonance. Differentiation should progress following the disease progress, until final diagnosis is established. In each case of arthritis (except infective arthritis) treatment with glucocorticoids should be employed, at the dose allowing suppression of symptoms. Depending on established diagnosis, this treatment should be accompanied by first-line medication, not later than from the 4th month. Preferred medication is methotrexate at a weekly dose of 15–25 mg. In the case of intolerance, it is suggested to use leflunomide. Lack of efficiency of monotherapy with either of the above mentioned medications is an indication for a combined treatment with several drugs modifying the course of the disease. Anticytokine drugs should be used in the case of inefficiency of such a procedure; this should be connected with full doses of methotrexate or, in exceptional cases, with another first-line drug. Treatment with rituximab and abatacept is reserved for patients in whom the above therapy is ineffective. Non-steroid anti-inflammatory drugs offer an adjuvant therapy option only during exacerbations. During all these years, physiotherapy should be continued. Treatment should aim at achieving and maintaining low activity of the disease, evaluated according to DAS 28 criteria.