Preliminary surveys based on lake and stream sediments have been carried out in southern Ontario as a possible basis for geoepidemiological research. The survey of cores of lake sediments involved 40 cores taken from 20 lakes in southern Ontario. Each core was examined for copper, lead, zinc, cadmium, and nickel soluble in acid as well as for fossil pollen that was used to date the sample material. There was a direct relationship between the age of the core material, the location from which the cores were collected, and the trace-element content of the samples. The stream-sediment survey involved the collection of 1,105 samples of material from a 1,165 km² area around St. Catharines, Ontario. In this study, eight elements were determined in the samples, and it was concluded that variations in the distribution patterns for lead, strontium, and zinc were caused by man’s activities in some cases and by natural causes in others. It is concluded that surveys of lake or stream sediments may be important starting points for the collection of geochemical data.