Compounds I-X were isolated from the water extractive of Cinnamomi Cortex, which shows anti-complement activity. Among them, the structures of I-VI were clarified on the basis of chemical and spectral studies. Compounds I and II were identified as cinnzeylanine and cinnzeylanol, respectively. Compounds III and IV were proved to be dehydrated products of I and II, respectively. Compound V was shown to be 19-hydroxylated IV and was named cinncassiol A. VI was identified as cinncassiol A 19-O-β-D-glucopyranoside.