The association between colonization with Candida spp., subsequent occurrence of invasive candidiasis and empiric use of amphotericin B was investigated prospectively in 139 neutropenic patients with hematologic malignancies. Treatment with amphotericin B was required in 67% of patients colonized in multiple non-contiguous body sites (multicolonized) versus 31% of patients colonized in single or contiguous sites (monocolonized) and in 21% of non-colonized patients (p = 0.0037 and p = 0.00026, respectively). Invasive candidiasis was documented in 22.2% of multicolonized versus 4.8% of monocolonized patients and in none of the non-colonized patients (p = 0.035 and p = 0.0036, respectively). Analysis of the spectrum of colonizing Candida spp. showed that multicolonized subjects were colonized with increased frequently by Candida albicans compared to monocolonized subjects, and that the association between multicolonization, invasive candidiasis and amphotericin B usage was statistically significant in patients colonized by Candida albicans but not in patients colonized by other Candida species. The association between Candida multicolonization and the occurrence of Candida infection seems to be confirmed by a double-blind placebo-controlled study performed in a small subgroup of the multicolonized patients treated with fluconazole.