Summary: Zoonotic diseases represent one of the leading causes of illness and death from infectious disease. Worldwide, zoonotic diseases have a negative impact on commerce, travel, and economies. In most developing countries, zoonotic diseases are among those diseases of major public health significance and contribute significantly to an already overly burdened public health system. In industrialized nations, zoonotic diseases are of particular concern for at-risk groups such as the elderly, children, childbearing women, and immunocompromised individuals. As defined by the World Health Organization, zoonoses are "those diseases and infections that are naturally transmitted between vertebrate animals and man with or without an arthropod intermediate." In an effort to increase our knowledge and understanding of current and probable future public health significance of zoonotic diseases, the Institute of Medicine's Forum on Emerging Infections hosted a two-day workshop on June 7-8, 2000. The workshop explored the forces that drive zoonotic diseases to prominence, and sought to identify more broad-based strategies and research programs that need to be developed for better understanding.