Rheumatoid arthritis is a systemic disease, which in clinical practice is defined as a long-term illness that can withdraw at certain times, but persists and reappears. There is no cure for RA, and the goal is to keep the disease under control, alleviate symptoms, and lead a more productive life for patients. A serious problem is pain in the small joints of the hands where redness, swelling, limited mobility and increased temperature in the affected joints are the main symptoms. If the disease is in a more severe form, fever and general weakness appears. Particularly problematic are rheumatic heart diseases of an acute or chronic nature, such as rheumatic fever, which causes lesions of the heart valves, insufficiency and inflammation of the myocardium and pericardium. RA is mainly defined as an autoimmune disease, in addition to which three quarters of RA patients have autoimmune problems. It is characteristic that in the polyarticular form of juvenile idiopathic arthritis the value of RF is constantly high. Several authors state that the presence of RF is not exclusively specific to RA. RFs are autoantibodies, mainly of the IgM type that are directed against the Fc fragments of IgG. As an animal model in the tests, we used white laboratory rats, of both sexes, aged about two months, kept in standard conditions with food and water regime ad libitum and the ambient temperature of stay 20 °C, with a light regime of 12:12 hours. The animals were divided into four groups: control of 20 males, control of 20 females, collagen type-II treated male group of 30 animals and treated female group of 30 animals. We applied the prepared colleague according to a standardized protocol in the back right wrist of the rats. A 0.1 ml collagen solution was given with 0.02 ml saline. We took 1 ml of blood for analysis, and after it coagulated, we centrifuged the tubes and decanted the serum into eppendorf tubes for analysis. The principle of the method is based on the RF-latex immune reaction between the RF and the analog antibodies with which the latex particles are coated, between which there is a reaction and the creation of a precipitate. Analyzes were performed on the Mini NEF TM Duinding Fait instrument. The results obtained according to the method used to determine the value for RF show that in all groups, in both genders and in both test periods, there are negative values for RF. According to this analysis method, any result obtained with a value lower than 30,380 IU/ml is taken as a negative value. We performed RF analyzes on the 30th and 60th day of RA induction, which is hypothetically likely to be a short period for the development of a more severe systemic illness, which is why there are no increased values for RF