Pneumonia is one of the prime causes of morbidity and mortality in children under five years of age. Objectives: To determine the frequency of pneumonia, to identify the causative organisms and the factors associated with death in children under 5 years of age. Methods: A prospective cohort study was performed in children 1 to 59 months hospitalized for pneumonia between January and June 2016 in CHUB pediatric wards. Results: A total of 237 children were hospitalized for pneumonia, i.e. 12.3% of hospitalizations.There were 133 boys (56%) and 104 girls (44%) with a mean age of 15.9 ± 13.8 months. The average time elapsed between onset of symptoms and hospitalization was 7.2 ± 6.1 days. The alveolar syndrome 185 cases (81%), alveolo-interstitial 34 cases (15%), alveolar and pleural 9 cases (4%) were the main radiological translations. Blood cultures were positive in 74 cases (31%) and the bacteria identified were: Streptococcus pneumoniae 42 cases (17.5%), Staphylococcus Aureus 23 cases (9.6%) and Klebsiella pneumoniae 9 cases (3.7%). HIV serology was positive in 19 cases (8%). Fifty-eight (58) children (24%) died. Factors associated with death were respiratory distress, hypoxemia and hypothermia. Conclusion: Pneumonia of children under 5 years of age is frequent and severe prognosis. Their mastery requires the strengthening of the national respiratory disease control program and the knowledge of risk factors.