In order to contribute to reduction of morbidity and mortality due to low acute respiratory infections in pediatrics, the objective of this study was to determine the epidemiological profile and to identify the factors favoring and those associated with the risk of deceased. We reviewed the cases of children aged between 1 and 59 months hospitalized between January and December 2015 in the pediatric intensive care unit of the CHU of Brazzaville and retained those whose diagnosis of discharge was an ALRI. The study variables were: epidemiological, clinical, paraclinic, diagnostic, therapeutic and evolutionary. For 2012 hospitalized children, 400 (19.8%) were hospitalized for an ALRI. There were 235 boys (58.8%) and 165 girls (41.2%) of average age. Infants aged 1 to 11 months were the most affected n = 260 (65%). They were insufficiently immunized with haemophilus influenza B and pneumococcus n = 378 (94.5%); Fully immunized n = 20 (5%), the average delay for consultation after the first symptom was 5.03 ± 3.86 days; Denutrition was rated n = 180 (45%), positive retroviral serology n = 19 cases (4.8%). The main nosological varieties were: bronchiolitis n = 223 (55.7%), pneumonia n = 145 (36.2%). One death was rated n = 65 (16.3%). The mortality determinants were: prematurity, vaccination status and HIV/AIDS infection. The frequency and severity of ALRIs necessitates a strengthened program of integrated management of childhood illnesses, and public health actions targeting the factors that promote and contribute to the risk of death.