Although Aspergillus spp infection is not the major cause of morbidity in Intensive Care Units (ICUs), mortality among patients treated for it is tremendous. Moreover, invasive aspergillosis (IA) is an independent risk factor of hospital costs and length of stay. The prevalence of this disease is inversely correlated with the immunocompetence of individuals; for instance, the incidence of IA among patients with leukemia is estimated as high as 12.7%. Although there is a significant improvement in the antifungal armamentarium, the appropriate treatment is still being given too late, mostly because of late diagnosis. As well as the diagnosis, the criteria for recognition of IA constitute a challenge. Objective The aim of this review, based on a case report, is to introduce the problem of poor diagnosis and treatment of IA, especially in the critical care settings. The presented scenario is an example which assists in showing the evidence-based medicine (EBM) approach to the treatment of fungal infections. Furthermore, to demonstrate the appropriate approach to diagnosis and treatment of invasive aspergillosis, the guidelines of The European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) are presented. Conclusions According to presented literature, Galactomannan assay enables early diagnosis and remains a specific and sensitive tool to diagnose Asppergillosis , both in serum and BAL fluid. The guidelines recommend voriconazole as a first line treatment in IA. Failure to detect and implement proper antifungal treatment may lead to fatal consequences, as in the presented case.