Neuropsychological effects occurring in young children exposed to low blood lead levels are now better known. This paper reviews the need to systematically screen for blood lead levels compatible with subclinical lead poisoning in young Canadian children. Using standard criteria for judging the appropriateness of this measure, the authors found no evidence to support such a practice in Canada. Case-finding is recommended in clinical settings for children with disorders suggestive of lead poisoning, increased lead absorption or exposure to a potential source of lead. A population survey is also recommended in the presence of a well-documented community environmental lead source. There is a need for common protocols across Canada for evaluating and treating children with blood lead levels compatible with subclinical poisoning. Areas of priority research are: the impact of persistent environmental sources of lead such as old paint and lead in water; defining criteria for selective screening; and methods of cost-effective environmental remediation.