The main viruses involved in acute respiratory diseases among children are: respiratory syncytial virus (RSV), influenzavirus (FLU), parainfluenzavirus (PIV), adenovirus (AdV), human rhinovirus (HRV), and the human metapneumovirus (hMPV). The purpose of the present study was to identify respiratory viruses that affected children younger than five years old in Uberlândia, Midwestern Brazil. Nasopharyngeal aspirates from 379 children attended at Hospital de Clínicas (HC/UFU), from 2001 to 2004, with acute respiratory disease, were collected and tested by immunofluorescence assay (IFA) to detect RSV, FLU A and B, PIV 1, 2, and 3 and AdV, FLU A and B in 9.5% (36/379), PIV 1, 2 and 3 in 6.3% (24/ 379) and AdV in 3.7% (14/379). HRV were detected in 29. 6% (112/379) Viruses are the most frequent agents that cause acute respiratory infections (ARIs) and are responsible for a considerable percentage of childhood mortality (Williams et al. 2002). In Brazil, some reports from different geographical areas has revealed the viruses as the main cause of respiratory infections, as related in the cities of Fortaleza (Arruda et al. 1991), Rio de Janeiro (Nascimento et al. 1991), São Paulo (Miyao et al. 1999, Vieira et al. 2001), and Curitiba (Tsuchiya et al. 2005.The most important viruses involved in ARI are: respiratory syncytial virus (RSV), influenzaviruses types A and B (FLU A/B), parainfluenzavirus (PIV), adenovirus (AdV), human rhinovirus (HRV), and the human metapneumovirus (hMPV) (Miyao et al. 1999, Kuiken et al. 2003, Tsuchiya et al. 2005). The last one was recently identified by Hoogen et al. (2001).RSV is the main cause of viral lower respiratory tract illness in children (Miyao et al. 1999), particularly in those younger than six months old (mo.) (Queiróz et al. 2002. In addition, RSV infections are responsible for most cases of severe symptoms such as bronchiolitis with recurrent wheezing and pneumonia (Calegari et FLU is a serious public health problem worldwide, were children constitute the age group most affected (Neuzil et al. 2002). Although many infections caused by FLU could be prevented by effective vaccination program, it has been predicted that a pandemic is likely to emerge in a near future (Cox et al. 2003), caused by a virus variant not covered by the current vaccine, requiring, thus, a constant epidemiological surveillance.PIV seems to have pattern of seasonal occurrence and is considered an important cause of respiratory illnesses, particularly among young children (Monto 2002).AdV infections are common in all age groups, causing both hospital-and community-acquired epidemics. Moreover, AdV has been associated with hospitalizations of near-fatal asthma patients (Tan et al. 2003) and with cases of acute otitis media in children younger than two years old (Monobe et al. 2003).HRV is responsible for the majority of common colds during winter, causing upper respiratory infections (Arruda et al. 1991, Savolainen et al. 2003 and is considered a risk factor for acute otitis media (Monobe at al. 2003). ...