Intramuscular and subcutaneous implantation of test materials in an animal model such as rabbits or rats provides a direct assessment of the acute or long-term tissue response to the toxic effects of leachable substances from candidate biomaterials. This model is used to comply with ISO 10993 for implant devices as well as devices which come into contact with other tissue for acute, subchronic and chronic evaluations. The implantation test is also a part of the USP Class Plastics test matrix.