Modern medical devices and prosthetics are typically made from multiple materials, therefore referring to the biocompatibility of a single material may not always be sufficient.

Since the immune response and repair functions in the body are highly complex, defining the biocompatibility of a single material with a single cell type or tissue is not adequate. Sometimes, in vitro testing is initiated first, in accordance with ISO 10993 or other similar standards, to determine whether a specific material/biomedical product is biocompatible. However, these tests are not sufficient to determine a material's biocompatibility; therefore, device safety must be supported by animal testing and clinical trials.

The purpose of Biocompatibility Testing is to measure the compatibility of a biomaterial or medical device with biological systems and to determine whether it has potentially harmful physiological effects. Biocompatibility Testing, one of the most important parameters of the conformity assessment process, is governed by the ISO 10993 series - Biological Evaluation of Medical Devices. Medical devices are expected not to produce physical, chemical, mechanical, allergic, toxic, or carcinogenic reactions in humans. Biocompatibility testing is crucial for monitoring, identifying, and scaling these effects.

Medical devices that come into contact with the human body must be tested by regulatory authorities for potential interactions and adverse side effects. For this reason, medical devices are categorized according to the nature and duration of body contact. Biocompatibility testing is a critical part of the regulatory approval process for medical devices.