The present literature review summarizes information about the diseases of the upper respiratory tract and the ears caused by opportunistic fungi. The factors responsible for the increased frequency of opportunistic infections, among which mycosis is the leading one, are given. The exogenous and endogenous risk factors are described. The main pathogens of opportunistic mycotic infections of the ENT-organs are listed. Special attention is given to the mechanism underlying the development of anti-colonial immunity of the upper respiratory tract and the ears and the formation of the antifungal immunity of the macroorganism as a whole. The data on the pathogenetic factors of mycelial and yeast-like micromycetes are presented. The main variants of the pathogenetic mechanisms, such as adhesion, invasive growth, and penetration, behind the formation of the mycotic lesions are considered. These biological properties of the fungi contribute to their ability to cause a wide range of pathological changes — from the superficial lesions of the skin and mucous membranes of the ENT organs to the deep invasive processes. The protective cellular and humoral immune reactions of a macroorganism that develop in response to the introduction of a pathogenic fungus are described. The review lists the main nosological forms of mycosis known to affect the ENT-organs with special reference to the leading role of the yeast-like fungi belonging to the genus Candida in the development of mycotic lesions of these biotopes (64.65%). The most pathogenic species, Candida albicans, prevails in the structure of the yeast-like fungi biome whereas the leading role in the development of mycosis of the ENT organs by micromycetes of mold belongs to the species Aspergillus niger.