Objectives: Infants and children with upper respiratory tract infection (URI) often have concurrent acute otitis media (AOM). Young infants have fewer specific symptoms than older children. The purpose of this study was to evaluate the usefulness of symptoms and other risk factors in predicting the presence of AOM in infants. Methods: Healthy infants, age less than four weeks, were enrolled and followed prospectively for up to age one year. Infants were scheduled for a research visit when their parents noted the onset of symptoms. At each URI visit, parents first reported the severity of symptoms. An investigator then diagnosed the presence or absence of concurrent AOM. Risk factors and symptom scores for infants with and without AOM were studied. Results: Infants (N = 193, mean age at first URI 3.9 +/- 2.5 months) experienced 360 URI episodes and 63 AOM events. Symptoms consisting of fever, earache, poor feeding, restless sleep, and irritability together (ETG-5) were statistically associated with the prediction of AOM (P = 0.006). A multiple variable statistical model (J-Score) that included day care attendance, age, severity of cough and earache best predicted AOM (P 0.001), with 95% specificity. Both ETG-5 and J-score yielded relatively low sensitivity for AOM prediction. Conclusions: In infants with URI in the first year of life, severity of symptoms was significantly associated with concurrent AOM. Daycare attendance, presence and severity of earache and cough added to better correlation. These observations may have clinical application in identification of infants at risk for AOM. (author abstract)