Introduction: Acute lower respiratory infection (ALRI: community-acquired and/or bronchiolitis) is one of the main public health issues for children under five years of age. The main purpose of this research was to describe the epidemiological prole, associated factors, and prognosis of ALRI in two hospitals in Popayán, Colombia. Materials and Methods: This was a cohort study. We included children from 2 months to 5 years of age with diagnoses of severe ALRI. Sociodemographic proles, clinical features, and prognostic factors were collected. The main outcomes under study were mortality, admission to ICU, and length of stay. Multivariable analyses were performed to establish the independent contributions of prognostic factors. Results: 121 patients were included. The incidence of ALRI was 4% ci95% [3,3-4,7] during 6 months of follow-up. Mortality during follow-up was 0,8% (ci95% 0,1–4,4) (one patient). Thirty-three percent of children required admission to ICU. The median length of stay was 5 days and length of stay in ICU was 4 days. Preterm birth was independently associated with ICU admission (or=5,1 ci95% [1,3-20] p=0,019). Discussion: The incidence of severe ALRI was 4%. Mortality was low and length of stay was short. Factors related to the diagnosis of ALRI in this cohort are consistent with those reported in the national and international literature, and the only independent prognostic factor for admission to ICU was preterm birth.