The alterations of the normal biological oxidoreductive balance can be due both to an increase of the plasmatic concentration of the free radical and the loss of the protective mechanisms. These conditions lead to the damages of cellular structure by the mechanism of lipoperoxidation. We have studied the lipoperoxidative effects of anesthetic drugs and the possible protective effect of the taurine. Two groups of 30 patients subjected to general anesthesia for a time of about 160 minutes, have been studied. The taurine has been administered in the second group, intravenously, before and during anesthesia. Blood samples were drawed in all patients in order to determinate plasmatic Malondialdehyde (MDA) and Glutathione peroxidase activities both in erythrocyte lysate and plasma. Our results revealed an increase of values of MDA and Glutathione peroxidase activities in the first group (without taurine). We think that this increase has been caused by the anesthetic drugs administration and that a protective cellular effect is developed by the taurine administration.