Abstract To enhance the rigor and reproducibility of SIV/macaque models of HIV/AIDS, it is essential to provide specific pathogen free (SPF) macaques to the research community. The NIH/ORIP has supported the development and maintenance of SPF macaque colonies since 2000 as a critical biomedical research resource particularly for SIV/macaque models of HIV/AIDS. Every pigtail macaque currently in the Johns Hopkins University SPF breeding colony meets the 4 viral agent SPF criteria set by NIH/ORIP, testing negative for Cercopithecine herpesvirus 1 (B virus), Simian Immunodeficiency Virus (SIV), Simian Retrovirus (SRV) and Simian T-lymphotrophic Virus (STLV-1). The SPF status of the JHU pigtail macaque breeding colony has been maintained for over ten years with no breaks detected by ongoing surveillance. The Virus Reference Laboratory (VRL, San Antonio, TX) performs all of our primate serology and PCR assays. Under the supervision of Dr. Eric Hutchinson, core director, all of the pigtail macaques at Johns Hopkins are tested annually by serology for the four SPF viral agents. In addition, all colony-born infants undergo two sequential PCR tests for SRV and STLV during the first year of life. Any rare additions to the colony from sources outside JHU are similarly tested by repeat PCR upon arrival in JHU quarantine. Our goal is to continue maintenance of SPF status of a valuable macaque national research resource for HIV/AIDS research. The specific aim of this Viral Testing Core is to maintain the SPF status of the colony by regular serologic and PCR testing for 4 viral agents: Cercopithecine herpesvirus 1 (B virus), Simian Immunodeficiency Virus (SIV), Simian Retrovirus (SRV) and Simian T-lymphotrophic Virus (STLV-1).