Three novel antioxidative serotonin derivatives were isolated from safflower oil cake (Carthamus tinctorius L.). Their structures were established as 4.4"-bis(N-pcoumarovl)serotonin (1), 4-[N-(p-coumarovl)serotonin-4"-yl]-N-feruloylserotonin (2), and 4.4"-bis(N-feruloyl) serotonin (3). Antioxidative activities of the compounds were measured by ferric thiocyanate method and DPPH method, and the compounds showed strong antioxidative activity.