OBJECTIVE: To evaluate the total resource consumption and the costs for diagnostics and treatments per patient with severe chronic polyarthritis (cp) from the third party payers‘ (TPP) perspective in Germany. METHODS: A retrospective cross-sectional cost of illness-study was performed. Patients (18 to 75 years) with acute disease activity of cp with a history of therapy failure with MTX over a minimum of 4 months or failure of more than one basic treatment were included. Hospital and practice data was abstracted from patients‘ records. Statistical analysis and cost evaluation were performed by using the SAS package. Cost data was taken from published German tariff and price lists. RESULTS: The mean age of the patients was 56 years, 71.2% were females. The mean onset of the disease was 11.2 years ago. The total average costs of outpatient care (n = 191 patients) were approximately 3,445 DM (95% CI: 2,981-3,907 DM) and for inpatient care (n = 76 patients) 10,433 DM (95% CI: 8,800-12,067 DM) per year. Concerning outpatient care drug therapy could be identified as the most relevant cost driver (69% of the total costs) followed by diagnostic procedures (10 %). The duration of the stay in hospital is the decisive factor for the costs of inpatient care from TPP‘s perspective in Germany. The average hospitalisation length was 19.5 days. Assuming a hospitalisation rate of 10 % the direct medical costs per cp patient and year were 4,488 DM. CONCLUSION: It could be shown that treatment of chronic polyarthritis is as cost-intensive as other chronic diseases. Because of the growing interest in the development of new concepts of patient care (e.g. disease management), further cost and outcome data should be assessed to show the relative value for money (e.g. with cost-effectiveness-analysis) in order to guarantee an appropriate allocation of resources.