Invasive fungal infections are a major threat for haemato-oncologic patients. The diagnosis is challenging, but an early and adequate therapy is crucial for survival. Echinocandins are suggested for initial treatment of critically ill patients with invasive candidiasis. Fluconazole is justified when the condition is stable and resistance is infrequent i. e. the incidence for Candida glabrata and Candida krusei is low. For invasive aspergillosis voriconazole is usually the drug of choice. Amphotericin B preparations, particularly the lipid formulations are adequate alternatives for invasive aspergillosis and for invasive candidiasis. First-line treatment of zygomycosis is performed with an amphotericin B preparation, whereas posaconazole is licensed for salvage therapy or oral step down treatment. Liposomal amphotericin B, amphotericin B colloidal dispersion and caspofungin are licensed for empirical anti-fungal treatment in persistent fever and neutropenia.