Objective.Interferon (IFN) regulatory factors (IRF) are transcriptional mediators of IFN-induced signaling pathways and are involved in immune response. We have analyzed for the first time the association of 2 IRF5 gene variants in the susceptibility to giant cell arteritis (GCA).Methods.Two hundred twenty patients with biopsy-proven GCA and 520 matched controls were assessed. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the IRF5 rs2004640 and for the IRF5 CGGGG insertion/deletion polymorphism using a predesigned TaqMan allele discrimination assay and by polymerase chain reaction amplification, followed by an ABI3100 sequencer, respectively.Results.A genotyping rate of 96% was achieved in this series of GCA patients. No significant differences were found in the genotype distribution between GCA patients and controls for both IRF5 gene variants. In this regard, similar genotype frequencies were found in GCA patients and controls. No significant differences were observed when GCA patients were stratified according to the presence of specific clinical features of the disease such as polymyalgia rheumatica or severe ischemic complications.Conclusion.Our results showed no association of IRF5 rs2004640 and CGGGG insertion/deletion polymorphisms in the susceptibility to and clinical expression of GCA.