In the first 12 weeks of persistence of arthritis symptoms a significant number of patients do not fulfil the criteria for the classification and diagnosis of a specific rheumatic disease. Such cases are recognized under the name of undifferentiated or early arthritis. Patients with early arthritis should be immediately referred to the rheumatologist, whose task is to implement all diagnostic tests necessary to establish, in the shortest possible time, the diagnosis and the presence of prognostic factors for the development of a chronic inflammation (Fig. 1). In case of revealing unfavourable prognostic factors, treatment with disease-modifying antirheumatic drugs (DMARDs) should be started immediately. Methotrexate is a drug of first choice with a dose of 25–30 mg per week recommended. The diagnostic standards for patients with early arthritis have been established in Europe and should be applicable in Poland as well.