On the basis of strong research evidence and consensus, (1) (2) (3) (4) human metapneumovirus is a leading cause of upper and lower respiratory tract infections in children. On the basis of research evidence and consensus, (3) (5) (6) (7) the clinical features of MPV-associated disease are similar to those of RSV. MPV is an important cause of asthma exacerbations, bronchiolitis, and pneumonia. Bacterial superinfection can occur.On the basis of research evidence and consensus, (2) (3) (8) the mean age of infection is 6 to 12 months, and nearly all school-age children are seropositive. However, infection can recur, likely in part due to impaired CD8+ T-cell response. On the basis of research evidence and consensus, (9) (10) (11) morbidity and mortality are the highest in patients who are premature, are immunosuppressed, or have underlying cardiopulmonary abnormalities. On the basis of research evidence and consensus, (2) commercially available diagnostic tests exist, and reverse transcriptase–PCR is the most commonly used. On the basis of consensus, because of a lack of relevant clinical studies, recombinant virus vaccines and monoclonal antibodies may be useful as prophylactics or therapeutics. (10)