The work is based on the determination of blood lead levels performed by the Central Laboratory of Toxicology of Heavy Metals in workers employed in various plants in the Katowice voivodship. The method of atomic absorption (ASA) was used for the determination. The Laboratory has participated successfully in the inter-laboratory programme of quality assurance. The study revealed that the highest exposure to lead occurs in overhaul and dismantle plants (group II) which work for large industrial establishments of non-ferrous metals (group I). Among establishments of group I higher exposure was found in raw material departments. Workers of certain professions such as fitters, refiners, smelters are particularly exposed regardless of the production profile of plants. The blood lead level is an important marks of occupational exposure to lead. Examinations should be performed only by laboratories involved in the programme of quality assurance of laboratory measurements.