Clinical applications and in vitro studies show that all antimycotics are most effective against infection when applied as early as possible. An early diagnosis is, therefore, essential. At this time for aspergillosis and particularly candidosis, a statement is only possible by combining several diagnostic methods. Inflammatory parameters like procalcitonin, C-reactive protein and proinflammatory cytokines are most important evidence of infection. Antigen tests are more significant by higher sensitivity. Attention should be focused on the detection of mannan by ELISA test, beta-glucan and D-arabinitol. Given the present research level in the field of proteomics, the diagnostic importance of transmembranal receptor proteins or other regulatory proteins seems promising.