The objective was to study the impact of blood lead level (BLL) on serum immunoglobulin levels (SIL; IgG, IgM, IgA) in people with high-risk professions. It has been characterized that BLL greater than or equal to 25 mug/dL can cause dysfunctions in different organ systems of the body, such as the immune system. A cross-sectional study was carried out in relation to this, by using a pretested questionnaire to collect data on demographic factors and socioeconomic status, which was completed by subjects studied, such as car battery shop workers, car painters and welders of car radiators and exhausts, printing office workers (typesetters and nontypesetters) who were aged between 15 and 70 years. Venous blood was sampled to measure the BLL (by atomic absorption spectroscopy) and SIL (by SRID). The results, when analysed, suggested a reduction in SIL with emphasis on IgG in comparison with standard levels.