The aim of our paper was to determine selected morphometric indices of the main fabric units of humus layers in soils with different vegetation cover and contaminated by heavy metals. The study sampled soil from three sites located about 4 km NW from a zinc plant. In all humus layers decomposed organic matter occurred mainly in form of fine excrements, originated from small soil arthropods, while macrofauna excrements were the absent. The dominance of soil mesofauna over macrofauna was probably attributed to elevated heavy metal concentrations. The high concentration of heavy metals affected the major soil components, but the kind of vegetation and the degree of cover of the soil surface were as important for the development of the humus layers as heavy metal contamination.