Since 1980, the Ontario government has conducted several blood lead screening surveys in children in several cities and regions of Ontario, Canada (1)(2). The blood lead concentrations in Ontario children has declined in both rural and urban areas over the past decade, this decline coinciding with the complete phasing out of lead in gasoline in 1990. Here, we evaluate this decline in terms of the geometric mean of the blood lead concentrations of 6014 children. The collection procedure of capillary finger-prick blood samples and the method for blood lead analysis by Zeeman graphite furnace atomic absorption spectrophotometry were described previously (3) and were used identically in all our blood lead analyses. The blood lead screening and surveys evaluated were done in the Toronto Western Health Unit in 1984, 1985, and 1988; the Peel Region, 1987; the Niagara Region, 1987; Southern Ontario, covering more-urban areas (Toronto, Windsor, etc.), 1984 (1); and Northern Ontario, covering the less-settled areas (e.g., Thunder Bay and Moosonee), 1987 and 1992 (2)(4). Gasoline sales data in Ontario were taken …