The gene FPR1 encodes the formylpeptide receptor (FPR), which is a G-protein-coupled receptor that mediates chemotaxis of phagocytic leukocytes induced by bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP). Agonist binding to FPR in phagocytic leukocytes leads to the activation of phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinases (MAPKs), and the transcription factor nuclear factor (NF)-kB via heterotrimeric Galphai proteins. FPR is involved in host defense against bacterial infection and in the clearance of damaged cells. Recently a large number of non-formylated peptide ligands for FPR have now been identified. Some of the new ligands (e.g. Ac1–26 from annexin) are endogenous in origin, and some come from pathogens that are associated with human diseases such as HIV, which have suggested novel roles for this receptor in the regulation of acute and chronic inflammation as well as host responses during HIV-1 infection.