Five new C-methylated flavonoids (class=""boldFont"">1-class=""boldFont"">5) together with seven known compounds have been isolated after chromatographic separation of the hexane and CH2Cl2 extracts of the roots of Pisonia grandis (Nyctaginaceae). Structural identification of the new compounds was accomplished by spectroscopic methods. The radical scavenging and antimicrobial properties of the isolates were investigated.