Co-morbidities (CoM) in rheumatoid arthritis (RA) are able to decrease quality of life due to the influence on disability and general health. Frequency of most important CoM was determinated in the presented analysis. The risk of disability progression triggered by CoM in the course of RA was assessed in the same time. Arterial hypertension, osteoarthritis and osteoporosis were the most common CoM diagnosed in the group of 440 hospitalised RA patients. Osteoporosis and Sjőgren syndrome presented the essential negative influence on disability. Special attention should be pay as well to cardio-vascular diseases, diabetes and hiperlipidemia in the context of disability progression.