In a study of associations between lead in blood and in tap-water, 113 blood samples and 140 tap-water samples of schoolchildren aged 9 to 12 years were analysed. Median and maximum values of blood lead were 8.3 and 34.0 micrograms/dl and of lead in tap water 24 and 2600 micrograms/l. Lead pipes were in use in some 50% of the houses. The pH values of the tap-water varied from 5.0 to 8.1. Both factors involved, i.e., lead pipes and acidic tap-water, have to be amended in order to reduce lead exposure in some regions or locations in Germany. This necessity is emphasized by increasing evidence of adverse effects to the central nervous system in children when blood lead levels exceed 10 micrograms/dl.