Soil humus contains a number of carboxyl and phenol groups which can form complexes of humus metal compounds with heavy metal cations called chelates. Chelate durability depends on the soil reaction and kind of metal ions. The formation of metal-organic complexes in the soil is very important as it prevents toxic heavy metals leaching from the soil due to at least partial detoxication of these substances. Previous research on the above issue was mostly focussed on the soils to which metal was supplied as a solution or readily soluble compounds. However, soils liable to pollution because of their location, pose a different problem. The present work aimed at the determination of the role of soil humus in the heavy metal bonding in the soils liable to traffic pollution. With regard to total heavy metal concentration levels, the soils analysed belonged to a group with a natural or elevated metal content. Organic substance is one of the main soil components binding copper and lead. The amount of these metals accumulated in the fraction bound to organic matter was significantly correlated with organic carbon content. Zinc and nickel are weaker by the organic substance of the soils studied.