A laboratory mesocosm experiment was performed to study the effects of copper-enriched sewage sludge application on a mesofauna community. For 12 weeks, characteristics and changes in this defined and artificial mesofauna community structure were monitored as well as the dynamics of leaf litter decomposition. The mesofauna community comprised six species of Collembola (Folsomia fimetaria, Isotomurus prasinus, Lepidocyrtus cyaneus, Mesaphorura macrochaeta, Parisotoma notabilis, Protaphorura armata), two species of acari Oribatida (Achipteria coleoptrata, Adoristes sp.), one species of acari Gamasida (Hypoaspis aculeifer) and one species of enchytraeid (Enchytraeus crypticus). Three treatments included the addition of 22 g dry weight (DW) sludge spiked with 0, 200 and 1,000 mg Cu kg−1 DW sludge in each mesocosm, and one treatment had 66 g DW sludge spiked with 1,000 mg Cu kg−1 DW sludge added in each mesocosm. Copper, complexed with sludge due to a favourable pH, had no effect on community and litter parameters when added to low amount of sludge. In contrast, tripling the sludge dose in addition to a high dose of Cu changed in time the sludge and leaf chemical composition as well as mesofauna community structure. Responses of the mesofauna to this treatment differed between species. The abundance of species such as I. prasinus, L. cyaneus, M. macrochaeta and P. notabilis decreased, whereas the abundance of H. aculeifer increased and became dominant.