In deep seated candidiasis, only 40% of blood cultures are positive. The aim of the study was to investigate circulating Candida albicans mannan and anti-mannan antibodies as a possible help for the diagnosis of deep seated candidiasis. We have compared the results to the detection of IgM by Elisa and antibodies by immunoflourescence. The best tests, in accord to their sensitivity and specificity, are the mannan antigenemia (43% and 100%) and IgM (86% and 100%) and have to be used together.