This study shows the incidence of RSV in 30 infants less than 2 years of age, presenting with a clinical picture suggestive of acute bronchiolitis to the emergency room of Cairo University Children Hospital during November 2001 together with 10 age and sex matched control. All the infants were subjected to full clinical assessment including measurement of oxygen saturation by pulse oxymeter, routine laboratory and radiological assessment and detection of the virus in nasopharyngeal secretion such infants using a rapid test Abbott TESTPACK RSV. RSV was found in 83.3% of the cases while 100% of the control group were negative for the virus. 86.6 % of the cases were less than 1 year of age, and 70% of them were males.