Résumé : Invasive pulmonary aspergillosis (IPA) is an increasingly recognised problem in critically ill patients. Little is known about how intensivists react to an Aspergillus-positive respiratory sample or the efficacy of antifungal therapy (AFT). This study aimed to identify drivers of AFT prescription and diagnostic workup in patients with Aspergillus isolation in respiratory specimens as well as the impact of AFT in these patients. ICU patients with an Aspergillus-positive respiratory sample from the database of a previous observational, multicentre study were analysed. Cases were classified as proven/putative IPA or Aspergillus colonisation. Demographic, microbiological, diagnostic and therapeutic data were collected. Outcome was recorded 12 weeks after Aspergillus isolation. Patients with putative/proven IPA were more likely to receive AFT than colonised patients (78.7% vs. 25.5%; P < 0.001). Patients with host factors for invasive fungal disease were more likely to receive AFT (72.5% vs. 37.4%) as were those with multiorgan failure (SOFA score >7) (68.4% vs. 36.9%) (both P < 0.001). Once adjusted for disease severity, initiation of AFT did not alter the odds of survival (HR = 1.40, 95% CI 0.89–2.21). Likewise, treatment within 48 h following diagnosis did not change the clinical outcome (75.7% vs. 61.4%; P = 0.63). Treatment decisions appear to be based on diagnostic criteria and underlying disease severity at the time of Aspergillus isolation. IPA in this population has a dire prognosis and AFT is not associated with reduced mortality. This may be explained by delayed diagnosis and an often inevitable death due to advanced multiorgan failure.