The interactions of the biomaterials with the host immune system is crucial for their functionality. This book aims to provide the reader with a better understanding of the role of the immune system in biomaterial applications. For this end, the book has dedicated chapters for i) explaining immune cells taking part in immune response to biomaterials/immune systems interface; ii) the effect of biomaterial shape, form and physicochemical properties on the response of immune system; iii) biofilm formation on implanted materials as a failure of immune system/biomaterial interactions; iv) tissue-specific effects of immune response and its consequences for tissue engineering and regenerative medicine; v) immune reaction in a clinical context (periodontology). In the field of biomaterials there are significant advances in using immunomodulation techniques to improve the success rates of implantable materials. For better understanding of such techniques it is required to have a full grasp of the biomaterial“immune system interactions. This would greatly enhance the understanding of why the human body reacts to implants in a certain way and how to improve the clinical outcomes by developing immune-instructive biomaterials.