This study aimed to determine Blood Lead Levels (BLL) in schoolchildren 6-14 years old exposed to industrial sources of lead and evaluated the role of socioeconomic condition. A cross-sectional study was conducted in an area likely to be exposed to industrial pollutants in northern Cali (i.e., distance and wind direction) and in a "non-exposed" area. In children in two schools of corresponding study areas, venous samples (5 ml) were collected to determine BLL by graphite furnace absorption spectrometry. Using regression models, we evaluated the association between risk factors to BLL and the effect of modification with variables of socioeconomic condition. We enrolled 350 schoolchildren. Schoolchildren in the exposed area had higher prevalence of BLL of ≥ 5 μg/dl (44.2 vs. 8.2 %, p = 0.000) than those in non-exposed area. A positive association was found between exposure and BLL of ≥ 5 μg/dl (prevalence ratios (PR), 6.68; 95 % confidence interval (95 % CI), 3.95, 11.29). Demographic characteristics and socioeconomic condition such as age (PR, 1.45; 95 % CI, 1.03, 2.04), sex (PR, 1.84; 95 % CI, 1.30, 2.60), race (PR, 2.32; 95 % CI, 1.39, 3.89) and socioeconomic position (SEP; PR, 2.02; 95 % CI, 1.35, 3.04) were statistically significant and independently associated with BLL. There was a synergistic interaction between exposure to the industrial zone and SEP for higher BLL (coefficient, 0.80; 95 % CI, 0.17, 1.43). Residence in the northern urban area of Cali exposed to pollutants of an industrial zone is associated to an increased risk of higher BLL, especially among children from low SEC who are at greater risk of exposure and susceptibility.