The aim of the present study was to define the reference Values for erythrocyte and liver tissue glucose-6-phosphate dehydrogenase (G6PDH), glutathione peroxidase (GPX), glutathione reductase (GR) and superoxide dismutase (SOD) activities and also reduced glutathione (GSH) levels in order to obtain basal data for subsequent toxicological investigations. In addition, the best storage conditions were determined for liver G6PDH enzyme. Male, apparently healthy Mus musculus (38) speciemens that had normal livers (histopathological data) were included in the study. G6PDH and GPX activities and GSH levels were measured by the Beutler method, and SOD aktivity was measured by the Fridovich method in the erythrocyte and liver tissues. GR activity in the erythrocyte was measured by the Beutler method, and GR activity in the liver was measured by the Staal method. The mean value (SD) of the levels of the enzymes and reduced glutathione in erythrocyte and liver tissues were as follows: G6PDH: 22.28 (3.53) U/g Hb, 2.38 (1.09) U/g liver; GPX: 134.88 (16.83) U/g Hb, 22.34 (4.70) U/g liver: GR:7.23 (1.58) U/g Hb, 2.47 (1.31) U/g liver; SOD: 4062.94 (929.41) U/g Hb, 553.71 (214.25) U/g liver; and GSH: 9.70 (1.64) mu mol/g Hb, 0.94 (0.22) mu mol/g liver. The best storage conditions for the liver the G6PDH enzyme were seven days at +4 degreesC, thirty days at -70 degreesC and thirty days at -20 degreesC.