In this study, age-related changes of GM1, GD la, GT1b fractions of gangliosides were investigated in whole brain of male Wistar albino rats, Insignificant increases were detected in GM1 values from the third to the 24th month, whereas GD1a and GT1b concentrations of ganglioside in 24-month-old rats decreased significantly as compared to 6-month-old rats. Although there were no significant differences in the GD1a/GT1b ratio of any groups. GM1/GD1a and Gm1/GT1b ratios were significantly increased as compared to 6-month-old rats. The increase in the ratios of gangliosides are not due to an increase of GM1 fractions: they result from a decrease of GD la and GT1b fractions of gangliosides. In conclusion, the concentration of ganglioside decreased with ageing. Copyright (C) 2000 John Wiley gr Sons, Ltd.