Prunioside A (1) has been isolated from an EtOAc-soluble extract of Spiraea prunifolia var. simpliciflora by a combination of chromatographic techniques. The structure was determined primarily by extensive NMR experiments. Compound 1 is a unique terpene glycoside. Its acetylated derivative (1a) inhibited nitric oxide production in murine macrophage-like RAW 264.7 cells in a dose-dependent manner.