This invention relates to a composition derived from Chinese herbal medicines, medicinal plants and extracts thereof, and to its use for preventing cancer and treating cancer and intensifying the effects of other anticancer drugs. More specifically, the composition of the present invention is derived from various Chinese herbal medicines or medicinal plants which have a long history of human consumption. The composition of the invention is obtained through specific techniques and has revealed good cytotoxicities on Malignant Melanoma Cells, Prostate Cancer Cells and Colon Cancer Cells, Lung Cancer Cells, Stomach Cancer Cells, Breast Cancer Cells and Liver Cancer Cells. The composition of the invention has also revealed obvious intensifying the effects of other anticancer drugs. Cancer presents special problems to the medical community which the present invention address.