Changes in soil respiration and dehydrogenase activity as effected by methane oxidation were studied in two loess soils under laboratory conditions. Stimulation of soil dehydro- genases reached the maximum at the beginning of the rapid CH4 and O2 depletion and intensive CO2 production. After 7-day incubation with CH4, dehydrogenase activity increased by 112 and 66% in an Eutric Cambisol and a Haplic Phaeozem, respectively (P<0.001). The Phaeozem respired more intensively than Cambisol, but the stimulation of the respiration by CH4 supply was evidently higher in the Cambisol. The methanotrophic activity of the soils tested varied in their relation to the respiration. The molar ratios of CH4 oxidized to O2 consumed to CO2 evolved was as 1 mol:1.44 mol:0.52 mol in Cambisol, and 1 mol:1.03 mol:0.24 mol in Phaeozem.