It is well-established that amyloid β (Aβ)-induced oxidative stress plays a crucial role in Alzheimer's disease (AD) and its cognitive deficits. HX106N is a water-soluble extract prepared from a mixture of the plants Dimocarpus longan, Liriope platyphylla, Salvia miltiorrhiza, and Gastrodia elata. These ingredients are traditionally used in various plant-based medicines for the treatment of neurological disease. In this study, we examined the effects of HX106N on memory impairment and oxidative stress caused by the intracerebroventricular injection of Aβ25-35 peptide in mice. For one week prior to Aβ25-35 peptide injection and 8 d after, mice were given oral HX106N. HX106N treatment reversed the Aβ25-35-mediated decrease in alternation percentage and latency time in the Y-maze and passive avoidance tests. Mice treated with HX106N showed decreased levels of thiobarbituric acid reactive substances (TBARS), a lipid peroxidation marker. Quantitative reverse transcription polymerase chain reaction (RT-PCR) demonstrated that HX106 treatment increased levels of heme oxygenase-1 (HO-1) in the hippocampus of Aβ25-35-injected mice, while having little effect on the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. In the murine hippocampal neuronal cell line HT22, HX106N was found to upregulate HO-1 expression at the RNA and protein levels as well as to protect cells from glutamate-induced oxidative stress. Taken together, our data suggest that HX106N may potentially act as a preventive and/or therapeutic agent for AD.