Respiratory syncytial virus (RSV) is the most important virus associated with bronchiolitis in infants and young children. The regulated upon activation, normal T-cell expressed and secreted protein (RANTES, also known as CCL5) appears to be a key player in the etiology of RSV-infected airway inflammation. In this study, we genotyped three single-nucleotide polymorphisms in the RANTES gene: -403G/A, -28C/G, and In1.1T/C in 59 infants with severe RSV bronchiolitis and 201 control subjects. The frequencies of the -403G/A+A/A, -28C/G+G/G, and In1.1T/C+C/C genotypes were significantly lower in patients with severe RSV bronchiolitis than in control subjects, and the frequencies of the -403A, -28G, and In1.1C alleles were significantly lower in RSV patients than in control subjects. The present results suggest that RANTES polymorphisms may confer risk for severe RSV bronchiolitis.