Piracetam has bee administered to young and old mice to investigate whether the age may differently modulate the activity of this centrally acting drug. After piracetam administration, old mice showed a notably greater increase of their brain tryptophan than young animals. Furthermore, piracetam significantly improves the learning capacity of young mice, but the drug is remarkably more active in improving the performance by old mice. These facts may then suggest that this compound is especially effective in restoring the neurobiological setting of the aging brain.