Background and Objectives: Tau protein and Aβ-amyloid have been studied as pathological aggregations, which form neurofibrillary tangles and amyloid plaques in Alzheimer’s disease brain. Tau protein plays a critical role in neuron that binds to microtubules and assists with their formation and stabilization. However, unbinding of hyperphosphorylated tau and microtubules leads to unstable and disintegrating state of neuron. The free tau proteins form neurofibrillary tangles. The purpose of this study is to evaluate efficacy of nine methanol extracts of Psidium guajava leaf; Nucifera nelumbo leaf; wild Ipomoea aquatic; Cleome rutidosperma aerial parts; Artocarpus altilis leaf; cultivated Ipomoea aquatic; Centella asiatica leaf; Mimosa pudica L. aerial parts; Nucifera nelumbo seed pod collected in the Mekong Delta by screening tau anti-aggregation activity in-vitro. Materials and methods: Nine herbs were collected, dried out and extracted with methanol. The half maximal inhibitory concentration (IC50) of methanolic extracts was measured by Thioflavin T assay at various concentrations. Results: Nine methanol extracts proved to reduce tau aggregation in vitro. Extracts from leaves of Psidium guajava, Artocarpus altilis and Nucifera nelumbo impressively inhibited tau aggregation with IC50 at 0.39 mg/mL, 1.05 mg/mL and 1.24 mg/mL respectively. Methylene blue was used as a positive control, with IC50 at 1.35 µM.