A coumaric acid analogue with a monoterpene moiety named floraosmanol A (1) was isolated from the flowers of Osmanthisfragrans var. aurantiacus. The chemical structure was elucidated on the basis of chemical and physicochemical evidence. Floraosmanol A (1) significantly inhibited nitric oxide .(NO) production in lipopolysaccharide- (LPS) activated RAW264.7 macrophages and the release of P-hexosaminidase as a marker of degranulation from rat basophile leukemia (RBL-2H3) cells. In addition, several cinnamic acid analogues were conjugated with geraniol and 3-methyl-2-buten-1-ol through an ester linkage. The inhibitory effects on NO production and the release of P-hexosaminidase of the synthesized compounds were examined for structure-activity relationships.