Subchronic treatment of aged mice with piracetam (500 mg/kg p.o. for 14 days) elevates N-methyl-D-aspartate (NMDA) receptor density by about 20% and normalizes the enhanced affinity of L-glutamate for the NMDA receptor. Since deficits at the level of the NMDA receptor might be one of the mechanisms underlying age-associated cognitive impairment, the effects reported for piracetam may be relevant for the cognition-enhancing properties of this drug.