Resumen La neumonia es una enfermedad inflamatoria, generalmente de caracter infeccioso, que afecta las unidades de intercambio gaseoso y que llega a producir diversos grados de alteracion en la difusion y/ o ventilacion alveolar, pudiendo llegar a poner en peligro la vida del paciente. El termino de neumonia adquirida en la comunidad (NAC) se le da a la infeccion del parenquima pulmonar que ocurre en ninos que no han estado hospitalizados en la ultima semana o que aparece despues de 48 horas del egreso hospitalario, que se acompana o no de sintomas y/o signos respiratorios de menos de 15 dias de evolucion. Se excluye de este grupo a todo paciente con algun tipo de inmunodeficiencia o patologia cronica graves que predispongan a ser vulnerables a la enfermedad al igual que pacientes con tuberculosos pulmonar y neumonia neonatal. Palabras claves: Neumonia, infeccion, parenquima pulmonar. Abstract Pneumonia is an inflammatory disease, generally of infectious character that affects the units of gaseous exchange, and produces various degrees of alteration in the diffusion and alveolar ventilation that may set in risk the patient’s life. The term of community acquired pneumonia (CAP) is given to the infection of the pulmonary parenchyma that occurs in children who have not been hospitalized in the last week or that appears 48 hours after hospitalization, accompanied or not by symptoms and/or respiratory signs of less than 15 days of evolution. All patients with some type of serious immunodeficiency or patients with chronic pathology, as well as those patients with pulmonary tuberculosis and neonatal pneumonia should be excluded from this group. Key words: Neumonia, infection, pulmonary parenchyma.