Guava, Psidium guajava L., is well-known tropic tree which is abundantly grown for fruit. It belongs to phylum Magnoliophyta, class Magnoliopsida and Myrtaceae family and has been found a lot in the Mekong Delta of Viet Nam. Antioxidant activity of different extracts from Psidium guajava L. leaves revealed that ethyl acetate and n-butanol extracts have the good activities. Processing of these fractions using repeated column and thin layer chromatographic techniques resulted in the isolation of four compounds, which have identified their chemical structures by spectroscopic techniques including avicularin (1), kaempferol (2), gallic acid (3), and protocatechuic acid (4). All the isolated compounds showed antioxidant activity using DPPH and ABTS scavenging assays. These results suggest that the leaves of guava  would be useful natural sources of antioxidants.