Open AccessThis study was carried out to evaluate acetylcholinesterase activity of methanol extract of Alnus rugosa L. stems and to determine the phytoconstituents in the plant extract. The acetylcholinesterase inhibition was detected using Ellman’s method and the methanol extract was subjected for phytochemical analysis to identify different phytochemical constituents present in the extract. The methanolic extract of A. rugosa stems has shown (IC50 = 0.588 mg/mL), assuming that the extract has compounds with a similar activity to neostigmine (IC50 = 1.87 μg/mL) and galanthamine (IC50 = 0.37 x10–3 mg/mL) which are considered to be the most effective compounds in the treatment of Alzheimer’s disease Phytochemical investigation of methanol extract of Alnus rugosa stems revealed the presence of triterpenes, flavonoids carbohydrates and tannins. These results prove that the methanol extract of Alnus rugosa stems seem of interest for further study as anti- Alzheimer agent.