New therapeutic approaches enable organ transplantations and guarantee longer survival for AIDS patients or patients with haematological neoplasia. The price for these medical advances is immunosuppression and thus enhanced susceptibility to opportunistic fungal infections. As a consequence invasive fungal infections are on the march in modern medicine. Therapeutic limitations and difficulties strongly demand for a deeper understanding of the interaction between the various fungi and the hosts' innate and adaptive immune defence system. This understanding is the essential prerequisite for a potential therapeutic approach, which may support specifically the insufficient antifungal attack of the host. In the present article, we therefore review the current knowledge of the role of the complement system as a central part of innate immunity and as a fine tuner of adaptive immunity in the pathogenesis of invasive fungal infections, such as aspergillosis, candidosis, cryptococcosis, paracoccidioidomycosis, blastomycosis and histoplasmosis.