The present study was undertaken to examine whether treatment with methylprednisolone could normalise (modulate) the biochemical dysfunctions in the skeletal muscles of mice in experimental trichinellosis. Our studies included investigations of two indices of the uncoupling of oxidative phosphorylation: RCI value (respiratory control index) and QO2 (oxygen uptake in state IV and in state III) as well as of two antioxidant enzyme activities: peroxidase (POX, E.C. 126.96.36.199) and superoxide dismutase (SOD, E.C. 188.8.131.52) in mouse muscles infected with Trichinella spiralis. Treatment with methylprednisolone was responsible for the normalisation of the activity of POX at 30 d.p.i. and was responsible for 50% decrease in stimulation of SOD activity at 43 d.p.i. At other points of measurement the drug showed no statistical influence on the activities of this enzymes. The drug had not statistically significant effect on the value of the respiratory control index and on the value of oxygen uptake.