Lobenzarit disodium (LBZ) is an immunomodulator and antioxidative drug developed and used successfully in Japan for the treatment of rheumatoid arthritis (RA). Studies in animals and humans have shown striking differences between the pharmacological profile of LBZ and nonsteroidal antiinflammatory drugs commonly used in the treatment of RA. LBZ does not inhibit the biosynthesis of prostaglandins and leukotrienes and is ineffective on acute inflammatory reactions induced in animals. Therefore, its usefulness in RA is ascribed to immunopharmacological properties of the drug. Currently, evidence is available that B- and T-lymphocytes are targets of LBZ's actions which regulates the functions of these cells. LBZ reduces IgE titers in serum of sensitized mice by activating suppressor T-lymphocytes and inhibiting anaphylactic shock induced by ovalbumin. These results provide evidence in favor of the potential use of LBZ in the treatment of allergic diseases, which must be elucidated in controlled double-blind clinical trials. The suppressive effects of LBZ on the function of activated B cells as well as in the production of anti-DNA antibody have been reported. These findings suggest that LBZ may be effective in the treatment of other autoimmune diseases such as lupus erythematosus that are also characterized by the production of autoantibodies from activated B cells. Recently, an open clinical trial in patients with systemic lupus erythematosus supports this point of view. Other potential therapeutic uses of LBZ are in autoimmune-related diabetes and in autoimmune liver disease which are documented in this review. LBZ also selectively antagonizes the contractile responses of isolated rabbit aorta strips induced by thromboxane A2-mimetic U-46619. This result provides evidence in favor of an antagonist of LBZ at the level of TxA2 receptors and supports the potential usefulness of LBZ in some cardiovascular disorders such as cardiopulmonary diseases and thrombosis. LBZ is a scavenger of oxygen-free radicals such as hydroxyl radicals, superoxide, peroxyl and singlet oxygen. This property contributes substantially to its pharmacological and therapeutic profile as well as its mechanism of action.