The study of the stability of saturated mono-, or polyunsaturated fatty acids, both esterified and not esterified, in plasma, circulating cells, and tissues is extremely important to validate the use of biological samples stored at low temperature in "biological banks", which are used for experimental, observational, dietary, or pharmacological studies. Since red blood cells are easily accessible cells, they are used as a marker of less-accessible tissues, especially in large-scale epidemiological studies. Data from the literature suggest that the addition of an antioxidant and the freezing of red blood cells do not cause any variation in the fatty acid composition for a period of 2-6 months up to 1 year. We evaluated the fatty acid concentration in red blood cells isolated from venous blood samples of one subject, preserved with butylated hydroxytoluene and N2 and stored at -80 degrees C for up to 2 years. Erythrocytes of venous samples of six subjects stored at -20 degrees C for 6 months without butylated hydroxytoluene and in the presence of air were used for comparison purposes. Our data demonstrate that a long storage time (2 years) does not significantly influence the erythrocyte fatty acid concentration when using very low temperatures (-80 degrees C) and antioxidants (butylated hydroxytoluene) in the presence of N2.