['To determine the memory-improving properties of huperzine A in aged rats with memory impairments naturally occurring or induced by scopolamine.', 'Morris water maze was used to investigate the effects of huperzine A on the acquisition and memory impairments.', 'During 7-day acquisition trials, aged rats took longer latency to find the platform. Huperzine A (0.1-0.2 mg/kg, s.c.) could significantly reduce the latency. In the probe trials on the eighth day, huperzine A (0.1, 0.2 and 0.4 mg/kg, s.c.) significantly increased the time in the quadrant where plateform had disappeared in aged rats. In the acute experiment, scopolamine (0.1 mg/kg, i.p.) significantly impaired spatial memory in the trained aged rats. Huperzine A (0.4 mg/kg, s.c.) significantly reversed the memory deficits induced by scopolamine.'] Does huperzine A ameliorate the impaired memory of aged rat in the Morris water maze performance?