Objective: To evaluate the prevalence of respiratory symptoms as the motive for emergency room visits by adult and pediatric patients, describing the major clinical syndromes diagnosed and the outcomes of the patients. Methods: A cross-sectional study conducted in the emergency room of a tertiary care university hospital. Between November of 2008 and November of 2009, we reviewed the total number of emergency room visits per day. Children and adults who presented with at least one respiratory symptom were included in the study. The electronic medical records were reviewed, and the major characteristics of the patients were recorded. Results: During the study period, there were 37,059 emergency room visits, of which 11,953 (32.3%) were motivated by respiratory symptoms. The prevalence of emergency room visits due to respiratory symptoms was 28.7% and 38.9% among adults and children, respectively. In adults, the rates of hospitalization and mortality were 21.2% and 2.7%, respectively, compared with 11.9% and 0.3%, respectively, in children. Among the adults, the time from symptom onset to emergency room visit correlated positively with the need for hospitalization (p < 0.0001), the length of the hospital stay (p < 0.0001), and the mortality rate (p = 0.028). Conclusions: We found a high prevalence of respiratory symptoms as the motive for emergency room visits by adult and pediatric patients. Our results could inform decisions regarding the planning of prevention measures. Further epidemiological studies are needed in order to clarify the risk factors for severe respiratory symptoms.