Introduction: Acute respiratory infections (ARIs) are the most frequent infections of childhood. They continue to be the most common leading cause of acute illnesses and account for many hospital admissions worldwide. Objectives: We determined the ARIs among children admitted to the Pediatric Department at Tripoli University Hospital over a period of 3 months. Patients and Methods: In this cross-sectional study on risk factors of ARIs among children <5 years old, diagnosis was based on clinical features according to WHO guideline criteria. A pro forma was used to collect information from the child's mother, including sociodemographic factors, clinical profile, perinatal history, family history of atopy or other associated medical problems, nutritional factors, environmental factors, and type of respiratory tract infection. Results: A total of 200 children with different respiratory illnesses admitted to the Pediatric Department were included. In this study, severe pneumonia was the most common illness; the age of the admitted cases ranged from 21 days to 4.5 years; 56.5% were boys and urban residents account for 76% from the total. Nearly 53% of the cases were from families with low income, and 3.5% of the participated children in this study had missed doses of the immunization schedule. In 88% of the cases, cough was the main presenting symptom followed by shortness of breath in 83.5%. Almost 58.5% of the children had a positive family history of atopy, and only 8% of cases were exclusively breastfed for their first 6 months of age. Conclusions: Lower respiratory infections are more prevalent among children under the age of 5. Younger age, male gender, urban residence, positive family history of atopy, lack of breastfeeding, and indoor air smoke were the common risk factors for ARIs.