Introduction and objectivesPortugal is one of the countries with the highest number of visits to the emergency department (ED), 31% classified as “non-urgent” or “avoidable.” The objectives of our study were to evaluate the size and characteristics of patients with pulmonary disease who overuse the ED, and identify factors associated with mortality. Materials and methodsA retrospective cohort study was conducted, based on the medical records of ED frequent users (ED-FU) with pulmonary disease who attended a university hospital center in the northern inner city of Lisbon from January 1 to December 31, 2019. To evaluate mortality, a follow-up until December 31, 2020 was performed. ResultsOver 5,567 (4.3%) patients were identified as ED-FU and 174 (0.14%) had pulmonary disease as the main clinical condition, accounting for 1,030 ED visits. 77.2% of ED visits were categorized as “urgent/very urgent.” A high mean age (67.8 years), male gender, social and economic vulnerability, high burden of chronic disease and comorbidities, with a high degree of dependency, characterized the profile of these patients. A high proportion (33.9%) of patients did not have a family physician assigned and this was the most important factor associated with mortality (p<0.001; OR: 24.394; CI 95%: 6.777–87.805). Advanced cancer disease and autonomy deficit were other clinical factors that most determined the prognosis. ConclusionsPulmonary ED-FU are a small group of ED-FU who constitute an aged and heterogeneous group with a high burden of chronic disease and disability. The lack of an assigned family physician was the most important factor associated with mortality, as well as advanced cancer disease and autonomy deficit.