Sickle-cell anaemia erythrocytes are under oxidative stress which contributes to some of the reversible and irreversible modifications observed in these cells. L-Propionyl carnitine, which protects myocardium, endothelium and erythrocytes from peroxidative damages and is able to stabilize damaged cell membranes, is also able to decrease the formation of thiobarbituric acid reactive substances which are produced by incubating erythrocytes with hydrogen peroxide in the presence of atmospheric oxygen or 95% N2-5% CO2 mixture. In these experimental conditions the increase of thiobarbituric-acid-reactive substances is significantly lower at 5 mM and 10 mM L-propionyl-carnitine concentrations. The formation of irreversibly sickled cells induced by 24-h incubation of sickle-cell anaemia erythrocytes under 95% N2-5% CO2 mixture is significantly decreased in the presence of 1 mM or higher L-propionyl-carnitine concentrations. The percent filtration of sickle red blood cells through micropore filters is significantly decreased at oxygen tensions between 20 and 40 mmHg. These in-vitro observations suggest that L-propionyl carnitine may be beneficial in maintaining the normal shape of sickle-cell anaemia erythrocytes at low oxygen tension and in decreasing the peroxidative damages which accumulate during the life of red blood cells.