This practice provides a series of experimental protocols for biological assays of tissue reaction to nonabsorbable biomaterials for surgical implants. It assesses the effects of the material on animal tissue in which it is implanted. The experimental protocol is not designed to provide a comprehensive assessment of the systemic toxicity, immune response, carcinogenicity, teratogenicity, or mutagenicity of the material since other standards deal with these issues. It applies only to materials with projected applications in humans where the materials will reside in bone or soft tissue in excess of 30 days and will remain unabsorbed. It is recommended that short-term assays, according to Practice F763, first be performed. Applications in other organ systems or tissues may be inappropriate and are therefore excluded. Control materials will consist of any one of the metal alloys in Specifications F67, F75, F90, F136, F138, or F562, high purity dense aluminum oxide as described in Specification F603, ultra high molecular weight polyethylene as stated in