For the first time new classification criteria for rheumatoid arthritis have been presented by the joint working group of American rheumatologists from the American College of Rheumatology and European experts from the European League Against Rheumatism (EULAR). The reasons for introducing new criteria and rules of establishing the criteria have been discussed. On the basis of the studies, performed when developing the new criteria, the working group has established the clinical symptoms and laboratory test results which constitute risk factors for development of chronic or erosive arthritis. The principles for use of new ACR/EULAR 2010 criteria for rheumatoid arthritis have been presented in detail. The possible effects of setting the new criteria have been taken into account.