This study assessed the development of microbial biomass, basal respiration, and the activities of dehydrogenase, urease, and acid phosphomonoesterase in sandy mine soils reclaimed for forestry and those developing under vegetation from natural succession. The mine soils contained significantly less organic C (Corg) and total N (Nt) than the natural forest soils. However, in some of them the microbial biomass and basal respiration attained values typical for the natural forest soils. The content of Nt proved to be the most important control on the microbial biomass, basal respiration, and the activities of dehydrogenase and phosphomonoesterase in the mine soils. All the microbial properties were positively related also to Corg content. The activities of dehydrogenase and urease depended strongly on microbial biomass (Cmic). Hence, high activities of these enzymes were determined in soils containing high Cmic. The acid phosphomonoesterase activity was also positively related to Cmic, but its activity was increased in the soils with low P contents.