Mycotic sepsis may be caused by obligately and facultatively pathogenic fungi. Obligately pathogenic fungi with dimorphism causing septic forms of cryptococcosis, blastomycoses, sporotrichosis, histoplasmosis, and coccidioidosis produce suppurative-necrotic lesions in the internal organs and the central nervous system. They run a course of primary diseases but occur rarely in our latitudes. More frequently, the septic forms of mycoses are due to conditionally pathogenic fungi (Candida, Aspergilli) and are manifested as a secondarily induced disease under conditions of various forms of immune deficiency of the host. Therefore, the main attention is paid to the discussion of protective reactions, particularly phagocytosis, since the latter has killer mechanisms against fungi. The presented data on the fungicidal system and detailed analysis of the functional properties of macrophages and leukocytes are important for the elucidation of the possibility of accumulation and transfer of medicinal biological substances directed at the elimination of the fungi.