Ras proteins play an important role in intracellular signal transduction pathways involved in cell growth and the mutated twas genes have been found in thirty percent of human cancers. Ras proteins (H-, K- and N-Ras) are small guanine nucleotide binding proteins that undergo a series of posttranslational modifications including the farnesylation onto cysteine 186 at C-terminal of Ras by farnesyl protein transferase (FPTase). This is a mandatory process for retention of transforming ability. Therefore, inhibitors of FPTase have a promising to be effective antitumor agents. In our screening program for FPTase inhibitors, the methanol extracts of 193 plants were screened for the inhibitory activity against FPTase partially purified from the rat brain. Extracts of 7species plants including Areca catechu, Saururus chinensis, Curcuma longa, Artemisa princeps, Paeonia suffruticosa, Spatholobus suberectus, Cinnamomum cassia, Cinnamomum japonicum inhibited more than 60% of FPTase activity at a concentration of $100;{mu}g/ml$.