The morphological, physical, chemical and biotical changes during the decomposition of the faecal pellets of the millipede Glomeris hexasticha were studied in microcosms in a field experiment during the course of one year. Microcosms were placed in the humus horizon of an oak forest. The C and N content of the faecal pellets decreased with total mass loss of up to 44 and 50% of initial content. The C/N ratio decreased from 23.7 to 20.9. Morphological changes, mass loss and changes of C and N contents were most pronounced on the 124th day of decomposition. This period was characterized by maximum respiration (4.24-mu-g CO2 . g-1 . d-1), maximum number of soil algae cells (52 . 10(3) . g-1), maximum abundance and biomass of testaceans (312,000 ind . g-1 and 12.4-mu-g . g-1, respectively), and by the development of omniphagous and predaceous nematodes (27.1 and 18.1 ind . g-1, respectively). Microorganisms utilizing easily decomposable organic substrates predominated in the first phases of the decomposition. In contrast, during the last stages, slowly growing microorganisms, oligotrophs and microorganisms utilizing more complex organic substrates dominated. The humus layer was more stable than that of the pellets in all examined characteristics. The rapid development of microflora and microfauna in the faecal pellets and its subsequent gradient changes showed the successional character of decomposition processes.