Because of their magnitude, their geographic and demographic characteristics, and their unique limnological properties, the Great Lakes appear to be especially susceptible to chemical contamination. The scientific basis for dealing with this contamination is very limited compared with the magnitude of the problem. This is particularly evident when the vast array of toxic xenobiotic substances of anthropogenic origin are considered. Major knowledge gaps exist on the critical transport pathways, ultimate fate, and ecological effects of toxic substances (of urgent importance are health effects on humans residing in the basin), as well as on the economic and social aspects of toxic management. The economic climate of the 1980s, however, is likely to severely limit the resources available for the conduct of research which is so badly needed. Consequently, it appears that the Great Lakes research community will have imposed upon it a markedly increased demand for information and a concomitant reduction in the resources available to accomplish the task. Finally, despite a pessimistic outlook for research support, there is optimism that the Great Lakes will respond positively, and in a relatively short time span (years as opposed to centuries), to the abatement of toxic inputs. Nevertheless, additional information on the processes affecting the distribution and fate of toxic substances is still critical to the understanding required to ensure effective remedial actions.