Adenosine and ACh contents in hippocampus, striatum region around the nucleus of basal meynert (NBM) and the frontal and temporal parts of rat cortex were measured by a high performance liquid chromotography-electronic detector (HPLC-ECD). Adenosine content in 18~20 month-old rats was significantly higher than that of 3~6 month-old rats, while ACh content in 18~20 month-old rats was lower than that of 3~6 month-old ones. Learning and memory impairment models were established by induction of SD rats with scopolamine (0.5 mg/kg, ip), which were injected with an adenosine receptor antagonist theophylline (1.0 mg/5 microliter, icv), and the step-down test was performed. The error frequency in the step-down test decreased significantly (P<<0.05), and the retention time was longer than that of control. Furthermore, ACh content increased in all the three different brain regions. The above results suggest that adenosine may play an important role in senile learning and memory impairment, and theophylline may improve scopolamine-induced learning and memory impairment by increasing ACh content. In consequence, theophylline could be a promising drug for ameliorating senile learning and memory impairment.