Due to their genetic proximity to humans, chimpanzees have historically been used in invasive biomedical research projects that study the immune responses in chimpanzees chronically infected with hepatitis virus, HIV, malaria, or with other medical conditions. However, new methods and technologies developed by the biomedical research community have provided alternatives to the use of chimpanzees in several areas of research, and, as a result, the use of chimpanzees in invasive biomedical research declined. In December 2011, the IOM issued a report that concluded that the use of chimpanzees in most biomedical research of human diseases was unnecessary because other experimental models have been developed and some studies can now be done using humans. Subsequently, NIH issued an interim policy suspending support of new research projects using chimpanzees while the agency considered the IOM report. NIH announced, in June 2013, that the majority of its owned chimpanzees would be permanently retired from invasive biomedical research and moved to the federal sanctuary as space became available, and that approximately 50 chimpanzees from among those it owned or supported, would be maintained for such research studies. However, after the June 2015 announcement by the U.S. Fish and Wildlife Service to add captive chimpanzees to the Federal List of Endangered and Threatened Wildlife, NIH announced, in November 2015, that it no longer planned to maintain any chimpanzees for invasive biomedical research. On February 2, 2016, NIH announced that it would limit its future support for research on chimpanzees consistent with the restrictions imposed on the federal chimpanzee retirement sanctuary. NIH currently owns or supports chimpanzees at four facilities. These facilities are: Alamogordo Primate Facility (Alamogordo), which is located on the Holloman Air Force Base in New Mexico, is operated by a for-profit contractor (Charles River Laboratories), and houses chimpanzees that are primarily descendants of the original research population associated with the U.S. space program. This facility houses only chimpanzees—no other types of primates—and, based on current agreements in place, may not accept any new chimpanzees into its facility. Chimp Haven, the federal chimpanzee retirement sanctuary in Louisiana, is a privately owned facility operated by a not-for-profit entity that provides lifetime care for retired chimpanzees. Under its contract with HHS, the entity receives federal funds for its operations but must also meet matching fund requirements. Chimpanzees that are housed at this facility are considered retired from invasive biomedical research. Michale E. Keeling Center for Comparative Medicine and Research at the University of Texas MD Anderson Cancer Center (Keeling) is a primate facility in Bastrop, Texas, that houses multiple other types of primates in addition to chimpanzees and is part of an academic facility that serves as both a center for biomedical research and as a center for veterinarian training. Southwest National Primate Research Center (SNPRC), which is a primate facility in San Antonio, Texas, houses multiple other types of primates in addition to chimpanzees and is part of a biomedical research facility—the Texas Biomedical Research Institute. It is the only facility among the four that, in addition to NIH-owned chimpanzees, houses NIH-supported chimpanzees. (For more information on the four facilities, see appendixes II through V at the end of this report.) NIH requires the four facilities housing chimpanzees owned or supported by NIH to comply with the recommendations in the Guide for the Care and Use of Laboratory Animals, Eighth Edition. Specifically, the NIH guidance requires the facilities to follow a framework for housing chimpanzees that offers environmental enrichment and animal well-being. For example, facilities are required to follow NIH recommendations on the physical characteristics of space within the facilities, such as allowing chimpanzees the opportunity to rotate into larger enclosures on a regular basis and providing access to natural materials and the outdoors to enhance their environmental complexity. Some examples of environmental complexity could include access to the outdoors, grass, mulch, and natural materials that provide climbing opportunities. The CHIMP Act Amendments of 2013 authorized appropriations for NIH to continue supporting chimpanzees in research facilities and at Chimp Haven. In addition, NIH indicated in a federal register notice that, although housing chimpanzees in larger groups has the potential to offer greater social complexity and more environmental stimuli than housing them in smaller groups, each facility has well-positioned, knowledgeable staff (i.e., veterinarians and primate behaviorists) who are able to determine a chimpanzee’s suitability for group or single housing. Since 1995, when NIH stopped breeding its captive chimpanzees, the number of NIH-owned and NIH-supported chimpanzees has been decreasing, and the proportion of NIH-owned and NIH-supported chimpanzees that are considered geriatric has increased. Captive chimpanzees have an estimated life expectancy of about 40 years and are considered geriatric at 35 years of age and older, with some captive chimpanzees living more than 50 years. Although the population is decreasing, as of January 15, 2016, NIH owned or supported 561 chimpanzees and expects that it will continue to own or support some portion of this population for twenty years or more. See table 1 for information on the total number of NIH-owned or NIH- supported chimpanzees by facility, which changes over time as chimpanzees die or are transferred to other facilities. NIH provides funding to all four facilities for the cost of care for the chimpanzees it owns or supports. Based on provisions in the CHIMP Act applicable to the federal sanctuary, Chimp Haven must match a portion of the federal funds received under its contract for operating expenses (such as expenses associated with the care of chimpanzees, including expenses for veterinary and other staff, food, medicine, enrichment activities, transportation, and associated overhead). Specifically, Chimp Haven is required to match 1 dollar for every 3 dollars (or 25 percent) in federal funds provided for operating expenses in cash or in kind. The other three facilities have no matching funds requirements. NIH fully funds the cost of the care for the chimpanzees that it owns at these facilities. For the chimpanzees it supports but does not own—which are located only at SNPRC—NIH contributes to the cost of their care. The CHIMP Act Amendments of 2013 authorized appropriations to NIH through fiscal year 2018 for the care, maintenance, and transportation of chimpanzees that NIH owns or supports. (See table 2.) No NIH-owned or NIH-supported chimpanzees are eligible for use in invasive biomedical research. As a result of NIH’s recent decision to no longer maintain a colony of chimpanzees for future invasive research, none of the 561 chimpanzees it owned or supported as of January 15, 2016, were considered eligible for such research, and three of the facilities reported that they had not used chimpanzees in invasive research during the period of our review, consistent with NIH’s efforts to phase out invasive biomedical research projects. However, all 561 chimpanzees were eligible for non-invasive research, even if retired to the federal retirement sanctuary, Chimp Haven. Non-invasive research studies include observational and behavioral studies and studies that involve the use of blood or tissue samples that are obtained during the course of regular medical care. Two of the four facilities—Chimp Haven and Keeling—reported that they were currently conducting non-invasive research with NIH-owned or NIH-supported chimpanzees. In addition, SNPRC officials reported that they previously provided tissue samples taken during the course of regular medical care to researchers for such research, but no longer do so. While Alamogordo officials reported that no research was currently underway involving chimpanzees at their facility, they reported that non-invasive research had taken place at their facility in recent years. NIH officials said that all of the chimpanzees it owns or supports may eventually be retired to Chimp Haven, though the timeframes are not yet determined. While NIH no longer allows invasive biomedical research on any of its owned or supported chimpanzees, according to NIH officials, chimpanzees are not considered to be officially retired until physically located at Chimp Haven. As a result, as of January 15, 2016, the 179 chimpanzees housed at Chimp Haven were considered to be retired, and NIH considered the remaining NIH-owned chimpanzees housed at the other facilities to be eligible for retirement to Chimp Haven as space becomes available there. Of the 301 NIH-owned chimpanzees that were eligible for retirement, 144 were housed at Alamogordo, 138 were housed at Keeling, and 19 were housed at SNPRC. SNPRC also houses another 81 chimpanzees supported by NIH, and they potentially could be retired to Chimp Haven if SNPRC opts to transfer ownership. See figure 1. Among the four facilities that currently house NIH-owned or NIH- supported chimpanzees, the average per-chimpanzee per-day costs incurred by NIH for their care have generally been lowest at Chimp Haven and highest at Alamogordo. The average per-chimpanzee per-day costs that NIH incurred for care provided to chimpanzees during the time period covering federal fiscal years 2013 through 2015 ranged from a low of $41 at Chimp Haven to a high of $61 at Alamogordo.