Macrophage inflammatory protein-1alpha (MIP-1alpha) and RANTES (regulated upon activation, normal T-cell expressed and secreted) were measured by enzyme-linked immunosorbent assay (ELISA) from virus-infected respiratory cell culture supernatants and from 100 nasal wash samples obtained from patients aged 8 d to 10 yr. The results of the nasal wash samples were analyzed in relation to the etiology of the viral infection. In vitro, respiratory syncytial virus (RSV) induced the production of MIP-1alpha, while both RSV and adenovirus were associated with the production of RANTES. Both MIP-1alpha and RANTES were detected in nasopharyngeal secretions from pediatric patients with acute upper respiratory tract RSV, adenovirus, influenza, and parainfluenza virus infection (p<0.001 by Fisher's exact test). As both of these chemokines have potent effects on the recruitment and degranulation of eosinophils and basophils, further understanding of their role in upper respiratory tract infections may provide valuable insights into the immunopathogenesis of respiratory viral infections.