We have examined in a series of experiments the pathomechanisms of the damage caused by the reperfusion following ischaemia of the striated muscle. The lipid peroxidation products (thiobarbitur acid-reactive materials [TBARS]) and the glutathion state were observed comparing the behaviour of the white and red fiber types. We have found significantly higher reduced and oxydated glutathion (GSH and GSSG) and TBARS values also in physiological circumstances in the red muscle fibers. At the end of a 4 hours ischaemia period no significant alteration was found in the above parameters though both the levels of GSH and GSSG were raised their ratio however did not change. We have measured expressed change with the elevation of the GSSG/GSH rate following a 1 hour reperfusion (108% +/- 22 in the white and 490% +/- 103 in the red muscle fibers) whereas the TBARS values still did not show significant elevation. In the second hour of the reperfusion the GSSG/GSH further elevated and beside this the expressed elevation of the TBARS could also be demonstrated (164% +/- 48 in the white and 152% +/- 28 in the red fibers. During the further reperfusion lasting altogether 12 hours we did not observe a significant decrease. The time sequence of these processes suggest that the lipidüperoxidation occurs only after the total exhaustion of the antioxidant reserves of the cell. The treatment with Methylprednisolon (MP), deferoxamine (DFO) and superoxid-dismutase+catalase (SOD+CAT) diminished in both types of fibers the raise of TBARS values.(ABSTRACT TRUNCATED AT 250 WORDS)