BACKGROUND Biomaterial is defined as "any substance or combination of medicine, artificial or natural origin, which can be used at any time, in whole or part by a system that controls, adds to, or restores any tissue, organ or function". ISO 10993-1: 2018 standard defines bio compliance law as "the ability of a medical device or tool to perform a selected program with the acceptable response of experts". Incompatible factors cause chemical reactions in patients, with little or no side effects. The body can respond in a sort of way after the installation of medical devices, so testing and improvement is important here. Therefore, testing and improvement in this field are important. Biocompatibility is required for any significant use of components or materials in medical devices. Inconsistent factors create negative biological responses in patients, which may have serious consequences. Biomaterials are substances utilized in medical devices, especially in applications where the device is touched, temporarily embedded, or permanently implanted within the body. Because of the significant impact of biocompatibility, many countries have imposed regulations on medical device manufacturers to meet biocompatibility specifications. Here is a brief explanation about the biocompatibility and incompatibility parameters of medical devices with a human body and its need for biocompatibility of medical devices with the human body. Medical devices have improved doctors' ability to diagnose and treat disease, which has led to significant improvements in health and quality of life. Thus, medical devices are prone to various incompatibility issues and procedures that affect the biological environment must be followed. KEY WORDS Biocompatibility, Material Interactions, Sterilization, Medical devices, Biocompatibility Testing, Incompatibility Factors.