The aim of the research was to evaluate the advancement of the naturalisation process that concerned the reclaimed area of the former the sulphur mine in Jeziorko. It was assessed by analising the diversity of earthworms populations from the chosen five spots (field I, II, X, XX and XXI) differentiated in terms of time and direction of reclamation. Earthworms were obtained by the mixed method, according to Zajonc. The results were analyzed statistically. On the field II reclaimed for the longest period in forest direction, all 7 species of Lumbricidae were found, whereas on field X (shorter reclamation) – 5 of them. In the open spaces of fields I, XX and XXI, representatives of the examined group were not present. On field XX and XXI, earthworms were preserved only within individual old trees (Malus Mill., Populus L. poplar) growing in this area even before the period of land degradation by the sulphur mines. Within the crowns of these trees, poor clusters consisting of 1 or 2 species of earthworms were discovered (A. rosea and/or A. caliginosa).