Of the tested steroidal saponins, Timosaponin AIII (TA3) most potently improves memory deficits. Timosaponin AIII increases the scopolamine-induced reduction in step-through latency by 17% (10 mg/kg), 28% (20 mg/kg), and 43% (40 mg/kg). During the acquisition trial, no differences in latent time are observed. Timosaponin AIII (20, 40 mg/kg, p.o.) potently inhibits this reduction of acetylcholine in scopolamine-treated mouse brain. The inhibitory effect of Timosaponin AIII is comparable to that of tacrine, which is used as a positive control.