Collagen-induced arthritis (CIA) in rat is an animal model that to a large extent mimics the criteria used for diagnosis of rheumatoid arthritis (RA). CIA in rat is a model that is characterized by both the T cell dependent inflammatory response and the collagen antibody dependent B cell response. CIA can be induced in susceptible rat strains (e.g. DA, Wistar, PVG, Lewis) with one single injection of homologous collagen type II in IFA, subcutaneously at the base of the tail. Disease onset is approximately two weeks after induction, most severe phase of arthritis is observed between 20-30 days after induction and the experiment can be terminated after 30-40 days.