Background: Pediatric acute respiratory infections (ARIs) represent a significant burden on pediatric Emergency Departments (EDs) and families. Most of these illnesses are due to viruses. However, investigations (radiography, blood, and urine testing) to rule out bacterial infections and antibiotics are often ordered because of diagnostic uncertainties. This results in prolonged ED visits and unnecessary antibiotic use. The risk of concurrent bacterial infection has been reported to be negligible in children over three months of age with a confirmed viral infection. Rapid viral testing in the ED may alleviate the need for precautionary testing and antibiotic use., Objectives: To determine the effect of rapid viral testing in the ED on the rate of precautionary testing, antibiotic use, and length of ED visit., Search Methods: We searched the Cochrane Central register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 4); EMBASE (1988 to December 2011); MEDLINE Ovid (1950 to November week 4, 2011); MEDLINE In-Process & Other Non-Indexed Citations (8 December 2011); HealthStar (1966 to 2009); BIOSIS Previews (1969 to December 2011); CAB Abstracts (1973 to December 2011); CBCA Reference (1970 to 2007); and Proquest Dissertations and Theses (1861 to 2009)., Selection Criteria: Randomized controlled trials (RCTs) of rapid viral testing for children with ARIs in the ED., Data Collection and Analysis: Two review authors used the inclusion criteria to select trials, evaluate their quality and extract data. We obtained missing data from trial authors. We expressed differences in rate of investigations and antibiotic use as risk ratios (RRs), and expressed difference in ED length of visits as mean differences (MDs), with 95% confidence intervals (CIs)., Main Results: We included four trials (three RCTs and one quazi-RCT), with 759 children in the rapid viral testing group and 829 in the control group. Three out of the four studies were comparable in terms of young age of participants, with one study increasing the age of inclusion up to five years of age. All studies included either fever or respiratory symptoms as inclusion criteria (two required both, one required fever or respiratory symptoms, and one required only fever). All studies were comparable in terms of exclusion criteria, intervention, and outcome data. In terms of risk of bias, one study failed to utilize a random sequence generator, one study did not comment on completeness of outcome data, and only one of four studies included allocation concealment as part of the study design. None of the studies definitively blinded participants.Rapid viral testing did not reduce antibiotic use in the ED significantly, neither clinically nor statistically. We found lower rates of chest radiography (RR 0.77, 95% CI 0.65 to 0.91) in the rapid viral testing group, but no effect on length of ED visits, or blood or urine testing in the ED. No study made mention of any adverse effects related to viral testing., Authors' Conclusions: Current evidence is insufficient to support routine rapid viral testing as a means to reduce antibiotic use in pediatric EDs. Results suggest that rapid viral testing may be beneficial in terms of reducing rates of antibiotic usage, urine investigations and blood investigations, but are not statistically significant due to lack of power. Rapid viral testing does reduce the rate of chest X-rays in the ED. A large trial addressing the effect on antibiotic usage is needed.