Introduction. Acute respiratory infections (ARIs) are a major public health issue and cause of morbidity and mortality in children under 5 years old. ARIs is a group of diseases ranging from self-limiting illnesses to bronchiolitis and pneumonia. The objective of the study was to identify the bacterial etiology of acute lower respiratory infections among hospitalized children under 5 years old. Material and methods. This was a descriptive cross-sectional study conducted in two hospitals from December 2020 to June 2023. The ethical approval was obtained from the Ethics Committee of the Institute of Mother and Child, Chisinau. All biological samples were taken using the nasopharyngeal aspirate technique. Standard bacterial culture techniques were used for isolation of bacterial agents. Results. Among 163 children, aged between 2 and 59 months, hospitalized with symptoms of lower ARIs, bacterial agents were identified in 76.1% of cases. The bacterial agents identified were as follows: Moraxella catarrhalis in 26.38% of cases, Staphylococcus aureus in 18.4% of cases, Streptococcus dysgalactiae in 11.65% of cases, Haemophilus influenzae in 9.2% of cases and Streptococcus pneumoniae in 8.58% of cases. At the same time, in 9.2% of the samples taken, other bacteria such as Acinetobacter baumanii, Klebsiella pneumoniae, Pseudomonas aeruginosa and others were identified, while in approximately 23.9% of the cases, the bacterial growth was absent. Conclusions. Prevention of ARIs in children is an essential component of the strategy to reduce infant mortality. Immunization against Haemophilus influenzae type b (Hib), pneumococcus, but also other infectious diseases, such as measles and whooping cough, is the most effective prevention method.