Evaluation of immuno-modulating properties of nanomaterials is important to develop new potential therapeutics for inflammatory diseases and cancer. Activation and suppressive effects of nanomaterials on immune responses occur through various interactions with different host proteins. They can also be engineered as carriers and/or adjuvants for different proteins or antigens. Particles, emulsions, and tubes/rods are the major formats of nanomaterials currently used in biomedical applications. Sometimes, nanomaterials induce side effects like undesired immunosuppression and toxicities, which are major concerns at present in designing optimal nanotherapeutics. This chapter summarizes different types of nanomaterials and their effect on immune responses.