Shorter relative telomere length in peripheral blood is a risk marker for some types of cancers and cardiovascular diseases. Several environmental hazards appear to shorten telomeres, and this shortening may predispose individuals to disease. The aim of the present cross-sectional study was to assess the effect of environmental exposure to lead on relative telomere length (rTL) in children. A cohort of 99 8-year-old children was enrolled from 2007-2010. Blood lead concentrations (B-Pb) were measured by graphite furnace atomic absorption spectrometry, and blood rTL was measured by quantitative PCR. The geometric mean of B-Pb was 3.28 μg/dl (range: 0.90-14.2), and the geometric mean of rTL was 1.08 (range: 0.49-2.09). B-Pb was significantly inversely associated with rTL in the children (rS = -0.25, p = 0.013; in further analyses both log-transformed-univariate regression analysis β = -0.13, p = 0.026, and R(2)adj 4%; and β = -0.12, p = 0.056 when adjusting for mothers' smoking during pregnancy, Apgar score, mother's and father's ages at delivery, sex and mother's education, R(2)adj 12%, p = 0.011). The effect of lead remained significant in children without prenatal tobacco exposure (N = 87, rS = -0.24, p = 0.024; in further analyses, β = -0.13, p = 0.029, and R(2)adj 4%). rTL was not affected by sex, the concentrations of other elements in the blood (i.e., cadmium and selenium concentrations), or oxidative injury parameters (total antioxidant status, 8-hydroxydeoxyguanosine and thiobarbituric acid-reactive substances). Lead exposure in childhood appears to be associated with shorter telomeres, which might contribute to diseases, such as cardiovascular disease. The inverse association between blood lead level and the telomeres in children emphasizes the importance of further reducing lead levels in the environment.