Fine-structural investigations were done with surface material and slides of pityriasis versicolor, Malassezia-folliculitis and seborrheic eczema. Aspects of the microorganism Malassezia furfur, such as its presence, its distribution on the skin surface, and its shape, and changes in the host skin tissue, such as the structure of the horny layer and signs of an inflammation were registered. Two main types of Malassezia-associated dermatoses were defined. One type is characterized by a considerable number of microorganisms, adhering to regular cells of the horny layer (exemplified by pityriasis versicolor), the other type is characterized by signs of an inflammation and a very low number of visible fungal cells (exemplified by seborrheic eczema).