The first version of Bacterial Endotoxins Test 〈85〉 appeared in USP 20–NF 15 (1980). The chapter was subsequently harmonized with the Japanese and European Pharmacopeias, and the first harmonized chapter appeared in USP 25–NF 20 (2002). Since its first publication, the content has changed very little, but years of experience, increasing knowledge, and more complex parenteral formulations suggest that the basic methodologies described herein could benefit from additional supporting information. The purpose of this information chapter is to provide additional background information and guidance for the performance and proper application of the compendial bacterial endotoxins tests.