We aimed to describe the viral etiology of acute respiratory tract infections in children aged 0-8 years admitted to Grigore Alexandrescu Hospital, the largest pediatric hospital in Romania. The patients had clinical diagnosis of pneumonia, bronchiolitis or viral respiratory infections and had been hospitalized between September 2010 and September 2011. The study was part of the "Molecular investigations of acute respiratory infections caused by non-influenza viruses, to assess the implications of infant and young child pathology" (2008-2011), a National Project II--42-164 (MIRVI). We included in the study 241 children that were swabbed in the first 8 days of the onset with the following symptoms during the previous 7 days: fever > 38 degrees C, AND cough or sore throat, and shortness of breath or difficulty breathing .We identified by RT-PCR 131 (54.4%) positive samples: 112 (85.5%) for a single pathogen, 18 (13.7%) for coinfection with two pathogens and 1(0.8%) for coinfection with three pathogens. The most frequent pathogen identified was respiratory syncytial virus (RSV) (40.18%), followed by Rhinovirus (RhV) (20.54%) and human Metapneumovirus (hMPV) (12.50%). We extrapolated our data to the National program of surveillance of SARI (severe acute respiratory infections). In this program, 191 children aged one month-8 years, were hospitalized in the same period, in which the highest percentage of positivity was due to Influenza viruses (62.65%), but RSV was identified with almost the same percent like in MIRVI (32.53%). It should be noted that among patients with pneumonia, bronchiolitis or respiratory viral infections were identified as the causal agent RhV.