The 15th annual conference of the International Society for Environmental Epidemiology (ISEE) will be held at the Hyatt Hotel in Perth, Western Australia, on the 24-26 September 2003. The theme of ISEE 2003 is "Traversing Boundaries" and the program includes high caliber keynote speakers who will consider current environmental epidemiological issues from different perspectives. The keynote addresses will present both Northern and Southern Hemisphere perspectives on these issues. The sub-themes also reflect the emphasis on traversing boundaries and the impact of environmental epidemiological research on policy and practice. These themes are "modified environments and environmental health," "applications of epidemiology in policy development," and "communities, health and advocacy." ISEE 2003 will bring together researchers representing a wide range of interests. Original research reports, case studies, workshops will be presented in the areas of air and water quality, reproductive outcomes, climate change, exposure assessment, risk assessment, complex mixtures, children's health, community responses to environmental health issues, methods in environmental epidemiology, and much more. Consistent with the tradition of prior ISEE conferences, ISEE 2003 will maintain high scientific standards in the papers and workshops in order to generate lively discussion in these sessions. The International Society for Environmental Epidemiology aims to foster the study of health and the environment. It provides a forum for the discussion of problems unique to the study of health and the environment. Membership is open to environmental epidemiologists and other scientists worldwide. ISEE provides a variety of forums for discussion, critical reviews, collaborations and education issues for environmental exposures and their human health effects.