We conducted this study to determine the contribution of respiratory viruses in 202 hospitalized children (1 mo-5 yr) with clinical evidence of acute lower respiratory tract illness (ALRI). Nasopharyngeal specimens were assayed for viruses detection by indirect immunoflourescent method. Viral agents were identified from 109 (54%) cases (9 cases had dual infection). The most commonly detected virus was parainfluenza virus 3 in 32 (15.8%) cases followed by respiratory syncytial virus 26 (12.9%) parainfluenza 1 and parainfluenza 2 each 13 (6.4%) influenza A 16 (7.4%), influenza B; 7(3.5%), and adenovirus 12 (5.9%). There were no demographic, clinical, radiologic or laboratory parameters except for recurrent wheeze (OR: 4.47; (95% CI: 1.98-10.73) and fever (OR: 3.27; (95% CI: 1.73-6.20), which could differentiate between patients with or without viral etiology.