OBJECTIVE: To estimate the coincidence of new otitis media (OM) for first nasopharyngeal detections of the more common viruses by polymerase chain reaction (PCR). New OM episodes are usually coincident with a viral upper respiratory tract infection (vURTI), but there are conflicting data regarding the association between specific viruses and OM. DESIGN: Longitudinal (October-March), prospective follow-up of children for coldlike illness (CLI) by diary, middle ear status by pneumatic otoscopy, and vURTI by PCR. SETTING: Academic medical centers. PARTICIPANTS: A total of 102 families with at least 2 children aged between 1 and 5 years (213 children; mean [SD] age, 3.7 [1.5] years; 110 male; and 176 white) were recruited from the local communities at 2 study sites by advertisement. MAIN OUTCOME MEASURES: New OM and CLI episodes and nasopharyngeal virus detections. RESULTS: A total of 176 children (81%) had isolated PCR detection of at least 1 virus. The OM coincidence rates were 62 of 144 (44%) for rhinovirus, 15 of 27 (56%) for respiratory syncytial virus, 8 of 11 (73%) and 1 of 5 (20%) for influenza A and B, respectively, 6 of 12 (50%) for adenovirus, 7 of 18 (39%) for coronavirus, and 4 of 11 (36%) for parainfluenza virus detections (P = .37). For rhinovirus, new OM occurred in 50% of children with and 32% without a concurrent CLI (P = .15), and OM risk was predicted by OM and breastfeeding histories and by daily environment outside the home. CONCLUSIONS: New OM was associated with nasopharyngeal detection of all assayed viruses irrespective of the presence or absence of a concurrent CLI. Differences among viruses were noted, but statistical significance was not achieved, possibly because of the low power associated with the small number of nonrhinovirus detections.