To investigate whether a biallelic polymorphism (A or G) occurring within the promoter region of the RANTES gene (position-403) is associated with polymyalgia rheumatica (PMR), giant cell arteritis (GCA) and rheumatoid arthritis (RA). A PCR-RFLP method was used to genotype cases and controls for this polymorphism. 3 groups of patients were examined; these comprised GCA patients who did not exhibit features of PMR (n = 30), PMR patients who did not exhibit features of GCA (n = 53) and RA patients (n = 99). All patients and controls (n = 65) originated from the area surrounding Lugo, Galicia, NW Spain. A significant increase in the frequency of allele A was found in PMR patients compared with normal controls. A marginal increase of this allele frequency was observed in RA but not in GCA patients. This is the first report of an association of a RANTES gene polymorphisms with PMR and RA. Our data suggest a possible role for of RANTES in the development of both PMR and RA.