Paclitaxel (PTX) is widely used to treat ovarian, breast, lung, pancreatic, cervical and other cancers, however, the cell uptake and utilization of PTX is greatly limited by its slow penetration rate and poor solubility in water. Therefore, it is of great interest to develop an efficient method for PTX delivery to improve its cellular uptake and utilization. A novel cell penetrating peptide, RRRRRWW (R7), is developed to accelerate the translocation of PTX into HeLa cells in the organic solvent-free system to suppress tumor growth. There is no significant cytotoxicity induced by the peptide alone even after 24 h incubation at 1 mM at 37 degrees C for both cancer cells and normal cells. In contrast, 30 min treatment with the R7/PTX complex leads to a significant decrease in the cell viability. The intracellular PTX concentration of the R7/PTX complex group is 3 fold that of the free PTX group. The in vivo animal experiments show that the tumor is dramatically suppressed by a tail vein injection of the R7/PTX complex. This system provides a novel approach for the delivery of PTX into tumor cells to efficiently suppress tumor growth.