The eradication of cancer is one of the important research subjects for humankind toward the 21st century. In the course of our research on potent cancer chemopreventive agents from edible plants and fungi, and from crude herbal medicines, we have found that various sterols and triterpene alcohols and their oxygenated derivatives showed activity in in vivo primary screening assay of antitumor promoters by inhibiting the inflammatory ear edema induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in mice. In this review, we discussed the inhibitory activity of sterols and triterpenoids toward TPA-induced inflammatory ear edema, and tumor promotion during two-stage carcinogenesis with 7, 12-dimethylbenz [a] anthracene (DMBA) and TPA. This activity was also noted in several other assays on antitumor promoters such as that on the activation of Epstein-Barr virus by TPA, and TPA-stimulated Pi incorporation in HeLa cells. Sterols and triterpenoids are minor but ubiquitous components in the human diet, and are considered to be non-toxic. These compounds may possibly prove useful for producing cancer chemopreventive agents.