There are no widely accepted predictors of pneumonia in wheezing infants and toddlers who present to the emergency department (ED). A 10-month retrospective review of ED visits of wheezing children < or = 18 months of age revealed the following chest radiograph (CXR) results: normal (21%), findings consistent with uncomplicated bronchiolitis or asthma (61%), focal infiltrates (18%), and other abnormalities (< 1%). Patients with focal infiltrates on CXR were more likely to have the following: a history of fever (p = 0.03, OR 2.1, 95% CI 1.0, 4.4), temperature > or = 38.4 degrees (p = 0.01, OR 2.5, 95% CI 1.1, 5.8) or crackles on examination (p < 0.0005, OR 3.9, 95% CI 1.7, 9.0). Selective use of CXRs has the potential to save health care dollars and limit unnecessary radiation.