Autoimmune diseases are polygenic and multifactorial, which target different organs either specifically or systematically. The prevalence of these autoimmune diseases is steadily increasing worldwide. Recently, many new drugs are successfully marketed to treat these diseases. However, currently available drugs are rapidly metabolized in their free form after administered into the body, thus cleared off before reaching to the target organ(s) in optimal concentrations. During last few decades, several carrier systems in nano-sized form have been developed to maintain sustained release of these drugs for longer period of time and also to moderate the toxicity profile of these drugs. These drug carrier systems include nano-sized liposomes, metallic nanoparticles (NPs), micelles, stimuli-responsive NPs, nano-emulsions and the nano-gels. These carriers are successfully demonstrated for the delivery of different drugs and their therapeutic or preventive potential has been assessed in different experimental conditions. In this chapter we have updated our current knowledge on these nano-sized carriers, and their in vitro and in vivo therapeutic efficacy using, rheumatoid arthritis (RA), as main example autoimmune disorder. © 2004 - 2023 Nova Science Publishers