Candida proliferate within the body of patients with deficient cellular immunity either by the haematogenous route or by adjacency. This condition is often found in hospital patients. It explains the increasing incidence of disseminated candidiasis. They are preferentially found in patients who have had complicated surgery, mostly of the gastrointestinal tract and the heart, or transplant surgery (except for kidney transplants), or who have had prolonged intensive care. Other patients concerned are neonates with a low birth weight, haemato-oncology patients, heroin addicts and AIDS patients. Clinical signs are usually unspecific. When there is widespread involvement, clinical signs can be defined by the secondary locations, especially within the kidneys, lung, endocardium and brain in surgical patients, and liver and spleen in haemato-oncology patients. Eye, skin, gastrointestinal tract, and indeed, muscle lesions which are easily accessible, should be looked for routinely. This helps to ascertain the diagnosis, by showing the presence of Candida in the tissues. Moreover, isolating Candida from places which are normally sterile confirms deep-seated candidiasis. However, the presence of Candida in urine, bronchi, or drainage fluids is only the witness of saprophytism. This underlines the usefulness of immunological tests, which should soon benefit from the availability of new kits for the detection of cytoplasmic antigens. Indeed, the search for antibodies or circulating metabolites do not provide, at present, significantly different results in patients who have only been colonised and in those who have a systemic candidiasis. Interesting results are only obtained by showing the presence of mannans, in research laboratories. For treatment, amphotericin B remains the standard antifungal agent, and the association of amphotericin B with flucytosine the recommended association. However, drugs such as the new triazoles, among which fluconazole is particularly well tolerated and efficient, may considerably alter the principles of treatment. Finally, combining a fungal decontamination of the gut should help reduce the very high death rate of systemic candidiasis.