BackgroundWheezing is a continuous musical sound that can be produced by oscillation of opposing walls of an airway that is narrowed almost to the point of closure 1; it affects approximately one-third of children at least once by the age of nine and is a significant cause of morbidity and mortality in young children worldwide2,3. While wheezing is only transient for most children, around 40% are still diagnosed with recurrent wheezing or asthma after the age of six years2,4. Wheezing is often induced by various respiratory tract infections, which include respiratory syncytial virus (RSV), human rhinovirus (HRV), human metapneumovirus (HMPV), influenza viruses, parainfluenza viruses (PIV), and coronavirus 2. While RSV is the leading cause of hospitalization for lower respiratory tract infection (LRTI) and first wheezing episode in infants3,5, recent improvements in virus detection through methods such as real-time reverse transcriptase polymerase chain reaction (qRT-PCR) have allowed investigators to better elucidate the important role of HRV in LRTIs, wheezing and asthma development. HRV is now known to be the most common virus associated with wheezing at ages 6-12 months and is the second most common virus detected among wheezing infants during the first six months of life, after RSV6,7.Developments in molecular diagnostics have also contributed to the discovery of HMPV and its role in respiratory illnesses8. Because studies show that virus-associated wheezing and LRTI during infancy are associated with the subsequent development of childhood asthma, it is important to determine which viruses are most strongly associated with wheezing and to assess other risk factors that contribute to wheezing, in order to develop interventions when possible6. Few viral epidemiological studies in the Middle East focus on the association between wheezing and respiratory viruses9,10. Our study aimed to determine the association of wheezing with respiratory viruses, demographic and clinical characteristics in young children.