It can be challenging to determine which findings are associated with focal infiltrates in young wheezing children. A prospective study of wheezing children < or = 18 months of age revealed focal infiltrates on chest radiograph in 23%. By use of multivariate analysis, findings significantly associated with focal infiltrates included grunting (OR 4.1, 95% CI, 2.0, 8.6) and oxygen saturation < or = 93% (OR 2.2, 95% CI, 1.1, 4.8); with a sensitivity and specificity of 12.5% and 97%, respectively. Variables not associated with focal infiltrates included first-time wheezing, fever, and tachypnea. The combination of grunting and oxygen saturation < or = 93% is highly specific and can be used to help diagnose pneumonia in wheezing infants and toddlers.