The author presents a new concept of complex relationship between the organism and Candida. According to this concept there is transformation of Candida carriage into invasive candidiasis of the mucous membranes. The idea is formulated on mixed-mycocenosis as association of fungal, bacterial, protozoic and viral biota. For the first time the notion of intermediate preinvasive form of candidiasis is given and clinical, morphological criteria of differential diagnosis between candida carriage, preinvasive and invasive candidiasis of mucous membranes are presented.