We studied the growth inhibitory activity of the emulsion from Brucea javanica fruit of B. javanica to human squamous cell carcinoma cells. The dose of 250 micrograms/ml at 96 hrs after drug exposure, it showed 42% growth inhibition, and at 500 micrograms/ml inhibited 56% of the cell growth. The effect of more than 50% of the growth inhibition was evident at more than 7 hrs after drug exposure. In the analysis of mechanism of the drug using a flow cytometry, the arrest in G1 phase of cell cycle was found during incubation of cancer cells with drug. These results suggested that the oil of B. javanica is useful as an anticancer drug.