The aim of the research was to examine possible role of exogenous phosphatidylserine in the modulation of the phospholipid turnover in the hippocampus and cognitive function of old rats. It has been determined that phosphatidylserine content in the hippocampus of the old rats intragastrically fed with lipids increased up to the level of phosphatidylserine in the brain of young animals. The exogenous phosphatidylserine had no effect on the phosphatidylethanolamine turnover and increase phosphatidylcholine synthesis in the hippocampus of old rats. Cognitive function of lipid-fed and control 24-month-old rats were studied with the aid of the active avoidance test in shuttle box. It has been determined that phosphatidylserine increased the number of active avoidances and decreased latency of active avoidance reaction in the learning session as compared with control rats.