From 1988 to 1998, we identified nine patients with Candida guilliermondii fungemia. Four of the five patients with nosocomial infection died, while all of the non-nosocomial cases survived, even though one half of them (2/4) did not receive any treatment. Nosocomial C guilliermondii fungemia is often associated with poor outcome despite aggressive antifungal therapy (Infect Control Hosp Epidemiol 2000;21:336-337). Within the past 2 decades, Candida species have emerged as major human pathogens and are currently the fourth most common cause of nosocomial bloodstream infection.1 The incidence of nosocomial candidemia has risen fivefold in the past 10 years, with Candida albicans being the most frequently isolated organism.2 This increase may reflect the increase in the number of immunocompromised patients and the more frequent use of invasive techniques that lead to extended hospitalization.3 Recent studies have documented a slight increase in the proportion of bloodstream infections due to species other than C albicans,1,4,5 Candida guilliermondii, described as the ascomycetous yeast of Yamadazyma guilliermondii, is found on human skin and as part of the genitourinary and gastrointestinal tract flora.6 It is well documented to cause endocarditis in intravenous drug addicts, infection in patients undergoing surgical procedures, and fungemia in immunocompromised patients.3,6 Because it is considered part of the emerging opportunistic fungi being recovered more frequently in severely immunocompromised cancer patients, we conducted this retrospective study of C guilliermondii fungemia in cancer patients over a 10-year period, with a special focus on nosocomial cases.