This study determined total concentrations and operational fractions of Zn, Pb, and Cd from sequential extraction in samples originating from the 0-15 cm upper layer of a 100-year-old calamine waste heap in Bolesław, Poland. Also investigated was the accumulation of the heavy metals in the tissues of Biscutella laevigata plants growing on the heap, and microbial activity (number and enzymatic activities) in the samples. Sequential extractions of heap material indicated that the exchangeable fraction (considered as bioavailable) of all the tested heavy metals was less than 0.5% of their total concentrations. Plant growth was found to have an effect on soil organic matter accumulation, number of fungi, enzymatic activity, and distribution of Zn, Pb, and Cd between operational fractions in the heap material. The number of isolated microorganisms and their enzymatic activities in samples with plant cover were almost the same as or higher than those in non-contaminated soils under vegetation with similar physico-chemical properties, as studied by other authors.