We studied the clinical characteristics and the initial supplementary test available in the emergency service, in aged patients with community-acquired pneumonia, as well as their mortality prognosis value. We assessed 190 patients attended consecutively during one year. Clinical, analytical and radiological data were registered. The parameters associated to a higher mortality were: age, absence of thoracic pain, reduction in the level of consciousness, leukocytosis, increased urea levels, aminotransferases, lactate dehydrogenase and reduction in prothrombin activity and pH. The data associated to a greater relative risk were: age above 80 years, absence of thoracic pain, prothrombin activity lower than 70% and ALT < 40 U/l. The presence of three to four of these variables had a sensitivity of 62% and a specificity of 94% in the prediction of mortality. In the multivariable analysis, the following variables remained significative: age, obnubilation and decrease of prothrombin. We stress the relevance of a high clinical suspicion, given the frequency of these cases with little symptomatology, in order to allow for an early treatment and the identification of right risk patients at the initial assessment.