Tiantai No. 1, a Chinese medicine predominantly composed of powderedRhizoma Gastrodiae,Radix Ginseng, and Ginkgo leaf at a ratio of 2:1:2 and dissolved in pure water, is neuroprotective in animal models of various cognitive disorders, but its molecular mechanism remains unclear. We administered Tiantai No. 1 intragastrically to senescence-accelerated mouse prone 8 (SAMP8) mice (a model of Alzheimer’s disease) at doses of 50, 100 or 150 mg/kg per day for 8 weeks and evaluated their behavior in the Morris water maze and expression of Alz-heimer’s disease-related proteins in the brain. Tiantai No. 1 shortened the escape latency in the water maze training trials, and increased swimming time in the target quadrant during the spatial probe test, indicating that Tiantai No. 1 improved leing and memory in SAMP8 mice. Immunohistochemistry revealed that Tiantai No. 1 restored the proliferation potential of Ki67-positive cells in the hippo-campus. In addition, mice that had received Tiantai No. 1 had fewer astrocytes, and less accumulation of amyloid-beta and phosphorylated tau. hTese results suggest that Tiantai No. 1 is neuroprotective in the SAMP8 mouse model of Alzheimer’s disease and acts by restoring neuronal number and proliferation potential in the hippocampus, decreasing astrocyte inifltration, and reducing the accumulation of amy-loid-beta and phosphorylated tau.