An ability to switch between a yeast-like form and a filamentous form was found among fumonisin-producing Fusarium verticillioides strains. These strains form yeast-like colonies in Sabouraud’s agar plates, containing 9%NaCl at 37°C in the dark. F. verticillioides strains in blood agar plates produce grass-green haemolytic reactions as a result of haemoglobin degradation. The possible role of these morphological forms in infectious diseases of humans and animals is discussed.