Community acquired pneumonia (CAP) continues being a condition of high prevalence, and potentially lethal. Streptococcus pneumoniae is the most frequent etiological agent of CAP. The objective of the present study is to describe the clinical and demographic characteristics, as well as the evolution, of adult patients admitted with CAP to the service of medicine of a Santiago general hospital (Hospital San Juan de Dios). 200 adults admitted with CAP diagnosis during winter 2003, were retrospectively studied. In 170 out of these 200 patients, diagnosis was confirmed. In average the patients were 68 years old. 51% of patients older than 65 y.o. had received influenza vaccination. High blood pressure, diabetes mellitus and heart failure were the most prevalent non respiratory comorbidities (59, 31 and 22% respectively). Chronic obstructive pulmonary disease was the most prevalent respiratory comorbidity (19%). The antibiotic therapy by election was a third generation cephalosporin, associated with a macrolide. The switch therapy was done in 140 patients (82%), using an antipneumococcal fluoroquinolone in 90% of the cases. The median period of hospitalization was 6 days. 40% of the patients required to be transferred to a clinical unit of higher complexity. In patients having a confirmed diagnosis of community acquired pneumonia lethality rose up to 11%. In only one of the patients, a Streptococcus pneumoniae resistant to Penicillin was isolated in the blood culture. Conclusion: CAP is a prevalent disease, especially in elderly patients, with specific clinical and demographic characteristics. CAP`s evolution and mortality rate can be known and modified