Hypericum sampsonii is an important medicinal plant used in Vietnam to treat many diseases such as backache, burns, diarrhea, and swelling. In order to study the chemical constituents in the aerial parts of H. sampsonii, five compounds, including two xanthones (1-2), and three benzophenones (3-5) were isolated from the aerial parts of the H. sampsonii with various chromatographic separations. Their chemical structures were established on the basis of spectroscopic data such as 1D- and 2D-NMR, HR-ESI-MS. Their anti-inflammatory activities were investigated by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 cells. Moreover, the DPPH radical scavenging was evaluated. As the obtained results, compound 5 showed the strongest inhibitory activity against LPS-stimulated NO production in RAW264.7 cells with IC 50 value ranging from 2.00 ± 0.34 µM.