Acute bronchiolitis is predominantly a viral disease. Respiratory syncytial virus is the most common agent, but other newly identified viruses have also been considered as causes. The aim of the present study is to determine the respiratory viruses causing acute bronchiolitis in hospitalized infants. Infants younger than 2 years of age who were hospitalized for acute viral bronchiolitis in a children's hospital between November 2011 and May 2012 were evaluated for the presence of viruses as etiologic agents using a realtime polymerase chain reaction method.A total of 55 infants were included in this study. The mean age of the children was 6.98±5.53 months, and 63.6% were male. In the 55 children, 63 viruses were detected. A single viral pathogen was detected in 47 (85.5%) patients, and two viruses were co-detected in 8 (14.6%) patients. Respiratory syncytial virus was the most common virus identified, accounting for 25 (45.5%) cases, followed by rhinovirus (n=9, 16.4%), and human metapneumovirus (n = 8, 14.5%).Although respiratory syncytial virus remains the major viral pathogen in infants hospitalized for acute broncholitis, more than half of bronchiolitis cases are associated with other respiratory viruses.