The current treatments for chronic inflammatory diseases cause severe side effects due to nonspecific drug accumulation. Nanotechnology opens the way to new therapeutic strategies that exploit the ability of immune cells, and especially of phagocytes, to internalize nanoparticles. The cellular uptake of nanoparticles requires specific interactions and is affected by the chemical and physical properties of the carriers. Therefore, optimizing these properties is crucial for designing nanodrugs for immunotherapy. In perspective, we discuss the nanoparticle-based approaches that have been proposed to induce tolerance in autoimmune disorders and lessen the symptoms of inflammatory diseases.