Among the systemic mycotic infections, disseminated candidiasis is the most frequent and is constantly on the increase. Candidiasis occurs in patients with particular risks, i.e., in oncologic neutropenic patients and in surgical patients after intraabdominal surgery. Independent predictive factors are multiple prior antibiotic therapy, the presence of intravascular devices and previous colonization by Candida, as well as the rupture of skin or cutaneous anatomical barriers. C. albicans is still the predominant species. Diagnosis of disseminated candidiasis is difficult and sometimes delayed. It relies essentially on a high index of suspicion, on blood cultures and the analysis of other samples (biopsies) by a combination of microbiological and anatomopathological procedures. The detection of Candida antigens, antibodies or metabolites still suffers from suboptimal sensitivity and specificity. Molecular diagnosis by amplification (PCR) is promising. The reservoir of Candida is mainly the human digestive tract, and a colonization stage usually precedes an established infection. Transmission of Candida by human carriage or through the environment could play an important role, particularly in intensive care units.