Hypercholesterolemia increases the oxidation of low density lipoprotein (LDL) which subsequently leads to atherogenesis. The oxidized LDL are also known to increase in vitro macrophage synthesis of glutathione. The purpose of this study was to investigate the relationship between lipid parameters and the glutathione system (glutathione, glutathione S-transferase) in total blood and within leukocytes. The glutathione and glutathione S-transferase were evaluated by spectrophotometric methods in sixty-two healthy volunteers (32 women, 30 men, mean age 39.9 +/- 7.7). No correlation was found between the level of blood cholesterol and the values of the blood glutathione system. However, a positive correlation between the values of glutathione and glutathione S-transferase in leukocytes and the blood cholesterol level was only found in women (r = 0.55 and r = 0.50 respectively, p < 0.01). We also found in men a positive correlation between body mass index and glutathione S-transferase in total blood and within leukocytes (r = 0.38, p < 0.05, r = 0.5, p < 0.01 respectively). No correlation was found between age, smoking and the values of the glutathione system. Our results suggest that the glutathione system in leukocytes is related to blood cholesterol levels. The fact that this positive correlation was only observed in women points to a possible role of estrogens in the regulation of the glutathione system which merits to be further studied.