We have synthesised the CXC chemokine receptor 4 (29-39) peptide, CXCR4[29-39]. This peptide is located in the N-terminal region of the receptor and is likely to be involved in the docking step of the receptor interaction with its natural ligand stromal cell-derived factor-1 chemokine, SDF-1. Preliminary experiments, performed in the presence of micellar detergents to model a membrane-like environment, show that the (1-17) segment of SDF-1 binds to CXCR4[29-39].