OBJECTIVE. Acute respiratory tract infections (ARTI) of viral origin are a frequent cause of pediatric consultations and hospital admissions. The aim of this study was to investigate the etiology of these infections in Gran Canaria, the Canary Islands, (Spain). METHODS. From May 2002 through May 2005, 1957 nasopharyngeal washings were collected from 1729 children presenting with ARTI to the Pediatric Emergency Unit. A rapid antigen detection method was performed in every sample to identify respiratory syncytial virus (RSV). An immunofluorescence assay (IFA) and cell culture (CC) was used in RSV-negative samples. RESULTS. Median age was 2 months (range, 0.03-119). A viral agent was identified in 1032 children (59.7%). RSV was detected in 769 children (74.5%). Other viruses identified, in order of frequency, were parainfluenza viruses, rhinoviruses, adenoviruses, influenza viruses, enteroviruses, and coronaviruses. Statistical differences were found between age and the type of virus detected: Adenoviruses caused respiratory infections in older children (median age: 6 months; range: 1-74). There were 6 mixed infections. Sensitivity of IFA as compared to CC was 55.8%, and specificity was 99.2%. CONCLUSIONS. Respiratory viruses are responsible for a large number of ARTI cases in children from Gran Canaria, RSV being the major cause. Viral identification is determinant for managing these patients and making a proper use of antibacterial and antiviral drugs.