Infection in the compromised host has been a topic of clinical concern, research and discussionfor over three decades.Our understanding of risk factors for infection, means of diagnosis, and therapeutic options hasincreased greatly during this period of time.However, the increasing numbers of patients who are immunocompromised, the changingepidemiology of infection, and the growing resistance of bacteria to commonly usedantimicrobial agents has made this problem one of the most persistent in infectious disease,hematology-oncology and general internal medicine.The compromised state occurs when any of the host's major defense systems are undermined in amanner that increases the chance of infection.Host defenses can be undermined by the underlying disease (myeloma, lymphoma, chroniclymphocytic leukemia), specific therapy of the underlying disease (steroids, cytotoxicchemotherapy) or an array of iatrogenic manipulations that occur when a patient is hospitalized(exposure to broad-spectrum antibiotics as prophylaxis or therapy, use of long-dwelling rightatrialcatheters, exposure to hospital pathogens).Invasive aspergillosis (IA) is a major problem in immunocompromized patients, as in humanimmunodeficiency virus (HIV) infection, after solid organ