The adverse effects of introduced birds and mammals on native taxa and ecosystems in Hawaifi have been long term, widespread, and severe. Impacts began at least 1,500 years ago with colonization by the Polynesians and their flora and fauna, and continued with their increasingly severe disturbance to the landscape, especially below 500 m elevation. Problems accelerated with the arrival of continental man in 1778, and continue to the present day with suspected deliberate releases of birds that threaten native species as recently as 1982. Alien vertebrates can affect native biota through predation, competition, depredation, and habitat degradation. Negative impacts can be subtle or dramatic, but evidence of importance is manifested in large percentages of extinct and rare taxa. In this paper, adverse effects of major bird and mammal introductions are outlined where possible for islands, vegetation zones, and rare taxa. Although much remains to be learned, suggestions for reducing negative effects of alien vertebrates can be made. These include: Enforcement of efficient quarantine procedures; sufficient support for enduring and complete vertebrate damage control programs (including research, management, and monitoring) on lands managed for preservation of native Hawaiian ecosystems and taxa; development of multiple and adaptable methods of vertebrate damage reduction; preservation and management of the most intact areas remaining in Hawai'i; and cooperation and communication among the agencies and special interest groups (including developers and conservationists) in land use planning on regional bases. Cooperative approaches, effective education and communication about the value of protected areas, and the increased usefulness of such areas for all citizens, are seen as particularly important in reducing continued damage to Hawai'ifs remaining native ecosystems by alien vertebrates.