The aim of this study was to determine the risk factors associated with high lead levels in school children. To that end a questionnaire was prepared to gather information about demographic and socio-economic characteristics of the children. Blood lead concentrations were obtained from capillary blood taken from 760 children at 13 schools in Istanbul and determined by atomic absorption spectrophotometry. The blood lead level ranged between 4.0 and 23 mug.dL(-1). The mean and the median values of the blood lead were 8.4 mug.dL(-1). Some 91.2% of the children (693) had blood lead levels less than or equal to 10 mug . dL(-1). Only 5 (0.6%) had blood lead levels over 15 mug . dL(-1). One child had a blood lead level above 20 mug . dL(-1). Household exposure to smoking, attending school near a main street and middle and upper-middle-class socio-economic status were found to be the most important risk factors for a high blood lead level. Children attending schools that were nearest to a main road exhibited higher blood lead levels than children in schools further from a main road. Our findings support the public health recommendations that children should not have household exposure to smoking, schools should not be located near main streets and unleaded gasoline use should be promoted.