The Canadian Health Measures Survey (CHMS), the most comprehensive direct health measures survey ever undertaken on a national scale in Canada, includes measurement of the heavy metals, lead, mercury and cadmium, which are toxic to humans at excessive levels. The geometric mean blood concentrations for lead, total mercury and cadmium were 1.37 microg/ dL, 0.76 microg/L, and 0.35 microg/L, respectively. Blood lead concentrations have fallen substantially since 1978, when national levels were last measured. Much of this decline may be attributed to the phase-out of leaded gasoline, lead-containing paints and lead solder in food cans since the 1970s. Fewer than 1% of Canadians now have blood lead concentrations above the Health Canada guidance value of 10 microg/dL. Similarly, fewer than 1% of Canadian adults have total blood mercury concentrations above the Health Canada guidance value of 20 microg/L for adults. CHMS data will be used to assess current population levels for a broad range of environmental chemicals, chronic diseases, nutritional status and infectious diseases; to provide a baseline for emerging trends, and to enable comparisons with other countries.