A total of 20 workers who were exposed to inorganic lead in two local firms (M and N) were studied. Lead concentrations in the air (PbA) at firm M exceeded the threshold limit value (TLV) of 0.150 mg/m3 established by Spanish and EC legislation, while atmospheric lead at firm N exceeded the action level of 0.075 mg/m3. In the same population, biological exposure indices (BEI) were also determined; these included lead in whole blood (PbB), erythrocyte activity of aminolevulinic acid (ALA-D), urinary excretion of aminolevulinic acid (ALA-U) and zinc protoporphyrin (ZPP). The relationship between the exposure parameters (PbA, PbB) and the biological activity indices (ALA-D, ALA-U, ZPP) were analysed statistically in order to obtain levels of significance, coefficients of correlation and regression equations. The high coefficients of correlation found confirm the usefulness of BEI in evaluating exposure to lead fumes and lead dust.