Oropharyngeal candidiasis in 512 HIV-infected patients at the late stages of the disease was studied with special reference to the clinical and microbiological characteristics of this condition. The diagnosis was established based on the results of the clinical and microbiological examination of the patients including investigation of the tissue samples taken from the oral cavity and the throat with the use of the device specially developed for this purpose. It was shown that the disease existed in various clinical forms the most common of which were monocomponent pathology represented by pseudomembranous candidiasis in 37.5±2.14% of the patients, the two-component mixed form (pseudomembranous candidiasis with concomitant angular chelitis) diagnosed in 27.5±1.97% cases, and the ternary form (the combination of pseudomembranous candidiasis, acute atrophic process, and angular chelitis) documented in 11.9±1.43% patients. The main clinical features of the disease included the combination of its various forms, multiple localization of the pathological process, and its polymorphous manifestations. Changes in the clinical course of oropharyngeal candidiasis associated with the progression of HIV from the 4A to the 4B stage were detected for the first time. They were shown to be accompanied by variations in the species composition and concentration of fungal flora in the crypts of the palatine tonsils and its sensitivity to fluconazole therapy.