In 1990, in response to the occurrence of Ebola virus (subsequently identified as subtype Reston) infection among cynomolgus monkeys imported from the Philippines, the United States implemented strict disease control measures for handling nonhuman primates during transit and quarantine and initiated importer facility compliance inspections. Disease control measures emphasized protection of workers from exposure, use of containment facilities and procedures, measures to prevent spread of infection among animals, and laboratory testing of animals that die or become ill during quarantine. From 1991-1995, no outbreaks of filovirus infection occurred, and only one other disease outbreak (caused by Mycobacterium species) was recognized. In April 1996, Ebola virus (subtype Reston) infection was identified in another group of cynomolgus monkeys imported from the Philippines. The disease control measures implemented since the first Ebola virus (subtype Reston) outbreak appeared to work well. Currently, the 27 registered importer facilities import approximately 8500 nonhuman primates annually, and mortality rates are <1.0%. Importer facilities receive regular inspections, and compliance with disease control measures and disease reporting is excellent.