Invasive aspergillosis and disseminated candidiasis are the two major manifestations of opportunistic invasive mycoses. Their incidence has risen considerably during the past decades, due to more intensive anticancer chemotherapy, organ transplantations, intensive care, and aggressive surgical interventions. Especially bone marrow transplant recipients are at risk for developing invasive aspergillosis. Whether the infection is acquired through contaminated water or through airborne spores is a matter of much debate. Candidemia and disseminated candidiasis commonly originate from the gastrointestinal tract. Abdominal surgery and mucosal damage due to anticancer chemotherapy are the majors factor through which gut colonization may lead to invasive disease. A shift in the epidemiology of disseminated candidiasis has been noted, with an increasing incidence of Candida glabrata, C. tropicalis and C. krusei strains.