A descriptive and longitudinal study was conducted in 32039 patients under 5 years with acute respiratory infections, discharged from Southern Children Teaching Hospital of Santiago de Cuba, from January 1997 to December 2010, to characterize the morbidity from these infections in those affected. Among the analyzed variables were age, sex, types of acute respiratory infections, and epidemiological factors that predispose to morbidity or death due to pneumonia, microbiological studies and morbidity rates from acute respiratory infections. Upper airways infections, patients aged 2 months to 4 years and male sex prevailed as well as anemia, poor breastfeeding practices, previous use of antimicrobials and teenage mothers. Prevalence rates showed little annual variability during the decade consistent with gross morbidity. [ABSTRACT FROM AUTHOR]