Treatment of AML patients during chemotherapy and SCT is frequently complicated by SI which may represent an obstacle to the antileukemic chemotherapy and transplant program. Antimicrobial prophylaxis, diagnostic approaches and antimicrobial therapy should be adapted to the infectious risk of the leukemic population. A crucial problem in the definition of these strategies is represented by the continuous change in the epidemiological patterns of infections as a result of the modification of risk factors in the leukemic population and of the global epidemiology of hospital and community acquired infections. In particular, the emergence of antibiotic resistant pathogens, particularly among gram negative bacteria, represents a serious problem which dramatically impacts on the antibacterial prophylaxis and treatments choices. A continuous epidemiology survey is required in order to better define proper prevention, diagnostic and treatment approaches. A common problem in the infections control in immunocompromised populations is represented by a late epidemiological consciousness. In particular, when new antileukemic strategies are implemented any change in the infectious epidemiology is frequently evidenced later retrospectively, but retrospective studies suffer of several drawbacks in the timely and proper collection of data.