A prospective study compared the levels of inflammatory mediators in nasal lavages from noninfected, asymptomatic subjects with the mediator content of lavages from the same subjects during naturally occurring rhinovirus colds. Samples wereobtained from 16subjects who experienced natural colds that could be attributed to rhinovirus infections. Kinin levels during symptomatic colds were significantly elevated (P < .01) compared with those measured when the subjects were noninfected and asymptomatic. Increases in kinins correlated with increased vascular permeability, as monitored by increased concentrations of albumin in lavages. In contrast, histamine levels in nasal lavages were not increased during symptomatic infections, suggesting that mast cell and basophil activation does not occur during rhinovirus colds. These data confirm and extend observations made during experimentally induced rhinovirus infections to the natural disease and are consistent with the hypothesis that kinins may playa role in the pathogenesis of symptomatic rhinovirus infections.