BACKGROUND: The number of reported cases of Legionnaires' disease has increased significantly over the last decade in Switzerland and abroad. Along with the number of cases, the volume of testing has increased as well, which has been partially attributed to a change in awareness of the disease. Yet, while there are numerous guidelines and recommendations for the case management of community-acquired pneumonia, little is known about how physicians in Switzerland perceive and manage Legionnaires' disease. METHODS: This study aimed to investigate physicians' awareness of Legionnaires' disease, their information resources and their approach to the diagnosis and treatment of pneumonia (and thus Legionnaires' disease). Using a semi-structured interview guide, we conducted in-depth interviews with physicians from different levels of care and from the German-, French-and Italian-speaking regions of Switzerland. RESULTS: We conducted 46 interviews with physicians from university, cantonal and regional hospitals as well as with general practitioners (GPs) from all three language regions. Overall, the physicians working in hospitals indicated a similar level of awareness of Legionnaires' disease, and comparable diagnosis and treatment approaches. The Legionella urine antigen test (UAT) was reported to be routinely performed in inpatients. In contrast, GPs indicated lower levels of awareness, reflecting the fact that they treat pneumonia cases empirically without identification of the causative agent, in accordance with current guidelines. The value of the diagnostic tests in general and the Legionella UAT in particular was considered to be dependent on the (preferred) antibiotic treatment approach. Some physicians saw the test as redundant, as its result would not influence treatment. This was tied to concerns about the UAT’s sensitivity and its limited use for the detection of Legionella pneumophila serogroup 1. Lastly, extrinsic constraints, such as financial and time considerations also affected physicians' testing and treatment preferences. CONCLUSION: Awareness of Legionnaires' disease is overall high, yet cases are mainly diagnosed and reported by hospitals. Improved diagnostic tools are needed to support physicians in reducing underestimation of Legionnaires' disease and optimise antibiotic stewardship without compromising patient health outcomes.