Arjunolic acid, an oleanene-type triterpene isolated from the rhizome of Cochlospermum tinctorium, its triacetate derivative, and their methyl esters were tested using the short-term in vitro assay on EBV-EA activation in Raji cells induced by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Their inhibitory effects on skin tumor promotors were found to be greater than those of previously studied natural products.