SBio (LifeSpan BioSciences) offers a catalog of 130,000 antibodies that have been tested for use in a variety of research applications, including immunohistochemistry, ELISA, Western blot, and flow cytometry. Antibodies can often be used in multiple assays, but they do not perform equally well in all assays. This is particularly true for immunohistochemistry (IHC). Many antibodies that perform well in other assays do not work well in IHC against formalin-fixed paraffin-embedded tissues (FFPE-IHC). In immunohistochemistry, antibodies may produce no signal, produce a weak signal, show nonspecific background staining that interferes with analysis, or show false positive signals. LSBio’s goal in immunohistochemistry validation is to identify for our customers those antibodies that perform well in FFPE-IHC. Out of the 130,000 antibodies in the LSBio catalog, 35,000 have been tested and received validation for use in IHC by LSBio or through collaborators or suppliers. Of these, 9,900 antibodies have been extensively tested in our Seattle laboratory and awarded IHC-plus™ brand validation. IHC-plus™ antibodies have been identified as the best reagents for use in FFPE-IHC.LSBio has tested and validated monoclonal antibodies (mouse, rabbit, rat), polyclonal antibodies (rabbit, goat, sheep, llama, chicken), and human single and double chain antibodies for immunohistochemistry. After fifteen years of experience performing contract IHC research, creating immunohistochemistry reports, and producing and testing over 12,500 antibodies in IHC, we have acquired a substantial body of experience regarding the best methods for validation of an IHC antibody. The purpose of this section is to share our knowledge of immunohistochemistry validation with you. The following summarizes our methods and approach toward immunohistochemistry (IHC) antibody validation.