The senescence-accelerated mouse (SAMP8) is an animal model used in studies of aging. The purpose of this study was to investigate the effect of different types of dietary lipids on longevity and age-related deterioration in memory in SAMP8 mice. Eight-month-old mice were fed diets with 5% lard (Lard group), 5% soybean oil (Soy group), 2% lecithin +3% soybean oil (Lecithin+Soy group) or 2% fish oil+3% soybean oil (Fish+Soy group), and learning and memory were examined by passive avoidance test at 8 and 10 mo of age. At the end of the experiment, the mice were killed, and the brain fatty acid composition was analyzed. The results indicated that the survival rates at 12 mo decreased in the order: Fish+Soy>Soy>Lecithin+Soy>Lard and were 50, 40, 30 and 20%, respectively. The rate of the lard group was lower than that of the Fish+Soy group, but this difference was not statistically significant. At 10 mo of age, the passive avoidance times of the Fish+Soy, Lecithin+Soy, Soy and Lard groups were 166, 170, 149 and 127 s, respectively. The passive avoidance times of the Fish+Soy and Lecithin+Soy groups were longer than that of the Lard group (p<0.01) at 10 mo. The brain DHA concentration was the highest in the Fish+Soy group SAMP8 mice, the linoleic acid levels was highest in the Soy group and the palmitic acid level was lowest in the Lard group (p<0.05). In conclusion, compared with SAMP8 mice fed a high saturated fatty acid diet, SAMP8 mice given a high poly-unsaturated fatty acid diet had higher brain concentrations of poly-unsaturated acid, better memory and greater longevity.