Candida species are the most common cause of fungal infections. Candida species produce infections that range from non-life-threatening mucocutaneous illnesses to invasive processes that may involve virtually any organ. Such a broad range of infections requires an equally broad range of diagnostic and therapeutic strategies. These guidelines summarize current knowledge about treatment of multiple forms of candidiasis for the Infectious Diseases Society of America (IDSA). Throughout this document, treatment recommendations are rated according to the standard scoring scheme used in other IDSA guidelines to illustrate the strength of the supporting evidence and quality of the underlying data (table 1). This document covers the following 4 major topical areas. The role of the microbiology laboratory. To a greater extent than for other fungi, treatment of candidiasis can now be guided by in vitro susceptibility testing. However, susceptibility testing of fungi is not considered a routine testing procedure in many laboratories, is not always promptly available, and is not universally considered as the standard of care. Knowledge of the infecting species, however, is highly predictive of likely susceptibility and can be used as a guide to therapy. The guidelines review the available information supporting current testing procedures and interpretive breakpoints and place these data into clinical context. Susceptibility testing is most helpful in dealing with deep infection due to non-albicans species of Candida. In this setting, especially if the patient has been treated previously with an azole antifungal agent, the possibility of microbiological resistance must be considered. Treatment of invasive candidiasis. In addition to acute hematogenous candidiasis, the guidelines review strategies for treatment of 15 other forms of invasive candidiasis (table 2). Extensive data from randomized trials are available only for therapy of acute hematogenous candidiasis in the nonneutropenic adult. Choice of therapy for other forms of candidiasis is based on case series and anecdotal reports. In general, amphotericin B-based preparations, the azole antifungal agents, and the echinocandin antifungal agents play a role in treatment. Choice of therapy is guided by weighing the greater activity of amphotericin B-based preparations and the echinocandin antifungal agents for some non-albicans species (e.g., Candida krusei) against the ready availability of oral and parenteral formulations for the azole antifungal agents. Flucytosine has activity against many isolates of Candida but is infrequently used. Treatment of mucocutaneous candidiasis. Therapy for mucosal infections is dominated by the azole antifungal agents. These drugs may be used topically or systemically and are safe and efficacious. A significant problem with mucosal disease is the propensity for a small proportion of patients to have repeated relapses. In some situations, the explanation for such a relapse is obvious (e.g., recurrent oropharyngeal candidiasis in an individual with advanced and uncontrolled HIV infection), but in other patients, the cause is cryptic (e.g., relapsing vaginitis in a healthy woman). Rational strategies for these situations are discussed in the guidelines and must consider the possibility of induction of resistance with prolonged or repeated exposure. Prevention of invasive candidiasis. Prophylactic strategies are useful if the risk of a target disease is sharply elevated in a readily identified patient group. Selected patient groups undergoing therapy that produces prolonged neutropenia (e.g., some bone marrow transplant recipients) or who receive a solid-organ transplant (e.g., some liver transplant recipients) have a sufficient risk of invasive candidiasis to warrant prophylaxis.