This book describes the role of titanium dioxide nanomaterials in cancer and autoimmune diseases. TiO2 nanomaterials are human safe, cost effective and stable chemical with numerous biomedical applications. The data showed in this book demonstrates that TiO2 nanomaterials ameliorated experimental autoimmune encephalomyelitis (EAE). We found that late onset with low severity of collagen induced arthritis (CIA) disease signs in CIA-TiO2 nanomaterials mice compared with CIA mice without treatment. Results obtained from in vivo animal models studies suggest that TiO2 nanomaterials have therapeutic potential in specific treatment of MS/RA and this may provide an effective novel therapeutic approach for other autoimmune diseases. Our findings suggest that TiO2 nanomaterials have immune suppressive role on splenocytes, macrophage cell lines and also showed anticancer activity in vitro and in vivo. More importantly, administration of Ti-O based nanomaterials ameliorated the clinical severity of EAE and CIA significantly by ameliorating pathophysiology, and presumably attenuating the immune response via HMGB1 cytokine release.