Background: Acute lower respiratory infections (ALRI), such as pneumonia and bronchiolitis, are the leading cause of morbidity and mortality in children under five years of age. Aim of the Work: To study ultrasonography findings in infants with acute lower respiratory tract infection and to test its sensitivity and specificity in comparison to clinical and conventional x- ray for diagnosis of childhood acute lower respiratory tract infection. Patients and Methods: The present cross sectional study was conducted on sixty patients were chosen according to inclusion criteria (fever with signs of respiratory distress) to compare chest ultrasonography to chest x-ray in diagnosis of children with acute lower respiratory tract infection. Results: In our study, diagnostic Accuracy of ultrasound was 93.45%, while diagnostic Accuracy of chest X- ray was 81% in patients' group. Sensitivity of ultrasound in cases of Bronchiolitis was 87.5% in comparison to chest X-ray was 78.1%, sensitivity of ultrasound in cases of pneumonia was 84.2% in comparison to chest X- ray was 52.6%. According to specificity, there is no difference in specificity between all patients' groupConclusion: In view of our study it can be concluded that, chest US offers an important contribution to the diagnostic procedures of acute lower respiratory tract infection in children, as Bronchiolitis, pneumonia and pleural effusion with higher sensitivity, specificity and positive predictive index comparable to chest X-ray.