Basic peptides such as human immunodeficiency virus type 1 (HIV-1) Tat-(48–60) and DrosophilaAntennapedia-(43–58) have been reported to have a membrane permeability and a carrier function for intracellular protein delivery. We have shown that not only Tat-(48–60) but many arginine-rich peptides, including HIV-1 Rev-(34–50) and octaarginine (Arg8), efficiently translocated through the cell membranes and worked as protein carriers (Futaki, S., Suzuki, T., Ohashi, W., Yagami, T., Tanaka, S., Ueda, K., and Sugiura, Y. (2001) J. Biol. Chem. 276, 5836–5840). Quantification and time course analyses of the cellular uptake of the above peptides by mouse macrophage RAW264.7, human cervical carcinoma HeLa, and simian kidney COS-7 cells revealed that Rev-(34–50) and Arg8 had a comparable translocation efficiency to Tat-(48–60). Internalization of Tat-(48–60) and Rev-(34–50) was saturable and inhibited by the excess addition of the other peptide. Typical endocytosis and metabolic inhibitors had little effect on the internalization. The uptake of these peptides was significantly inhibited in the presence of heparan sulfate or chondroitin sulfates A, B, and C. Treatment of the cells with the anti-heparan sulfate antibody or heparinase III also lowered the translocation of these peptides. These results strongly suggest that the arginine-rich basic peptides share a certain part of the internalization pathway.