We describe the cloning of a human gene, named ChemR1, encoding a new putative chemokine receptor sharing 48% identity with CC-chemokine receptor (CCR)4 and 44% identity with CCR1. It displays four extracellular cysteines that are conserved among all other chemokine receptors. ChemR1 transcripts were detected by Northern blotting in the T lymphoblastic cell lines Jurkat and MOLT-4, but not in the pre-B lymphoblastic cell line JM-1. ChemR1 receptor transcripts were also detected by reverse transcription and polymerase chain reaction analysis in unstimulated CD4+ and CD8+ T cells and polymorphonuclear cells prepared from peripheral blood. The chromosomal localization was performed by radiation hybrid mapping and testing of a panel of yeast artificial chromosome clones. This allowed the assignment of the ChemR1 receptor gene to the p21.3-24 region of human chromosome 3, in close proximity with the functionally characterized CCR. Future work is required to identify the ligand(s) of this new chemokine receptor and to define its role in the recruitment of white blood cell populations.