The use of beta-(beta) emitting radionuclides for radiosynoviorthesis (RSO) has been a well established therapy for inflammed joints for more than 40 years. Radionuclides are often applied to patients with rheumatoid arthritis as local therapy. The choice of the radionuclide is empirical. The evaluation of the therapeutic success is mainly based on the improvement of the joint motion. MRI and other radiological examinations have not been proved to be reliable for diagnosis of the therapeutic success. The aims of this manuscript are to familiarize physicians with the different radionuclides, to explain the therapeutic success which can be expected due to dosimetric data, and to present the three phase bone scintigraphy as a valuable instrument for the evaluation of the therapeutic success.