Introduction: Respiratory infections are an important cause of morbidity and mortality in immunocompromised patients. Bronchoscopy with BAL is an important tool to assess the role played by infectious agents in immunocompromised patients with suspicion lower respiratory tract infections. Methods: Immunocompromised patients with a suspicion for LRTI underwent diagnostic BAL and we aimed to quantify its impact up to 30days after bronchoscopy after routine implementation of multiplex PCR for respiratory viral infections. The primary composite outcome consisted of pre-defined modifications in the management of the immunocompromised patients following BAL. Results: A total of 2,666 visits from 1,301 patients were included in this observational, single-center study performed at the University Hospital Basel from October 2009 till September 2017. Immunosuppression was classified as haematological (n= 1,040; 544 patients), solid organ transplantation (n= 666; 107 patients) and other causes (n= 960; 650 patients). BAL led to a change in management in 52.36% (n= 1,396). This percentage, as well as the 30-day mortality, differed significantly among the 3 groups. Age, CRP levels and etiology of infection significantly affected 30-day mortality. In 92.68% (n= 646) of respiratory viral infections only one viral agent was detected whereas in 1.89% (n= 50) a combination of at least 2 viral agents was found. Conclusions: BAL leads to changes in management in the majority of immunosuppressed patients. The routine introduction of viral multiplex PCR has markedly contributed to these results.