The objective of this study was to provide an updated meta-analysis of the efficacy and safety of huperzine A (HupA) in Alzheimer's disease (AD). We searched for randomized trials comparing HupA with placebo in the treatment of AD. The primary outcome measures were mini-mental state examination (MMSE) and activities of daily living scale (ADL). Data were extracted from four randomized clinical trials and analyzed using standard meta-analysis and meta-regression methods. Oral administration of HupA for 8-24 weeks (300-500 microg daily) led to significant improvements in MMSE and ADL. The results of meta-regression showed that the estimated effect size of MMSE and ADL was increased over the treatment time. Most adverse events were cholinergic in nature and no serious adverse events occurred. Huperzine A is a well-tolerated drug that could significantly improve cognitive performance and ADL in patients with AD.