Pentoxifylline, a phosphodiesterase inhibitor, produces a marked reversal of an age-dependent spatial memory deficit in Fischer 344 strain male rats. Performance of 26-month-old animals treated chronically with pentoxifylline approached that of 3-month-old controls. The effect was not dependent upon concurrent administration of the acetylcholine precursor choline chloride. It is concluded that the pentoxifylline-induced reversal of the age-dependent memory decline is not dependent on any presumed facilitation of acetylation and utilization of exogenously supplied transmitter substrate.