Abstract: Recently, we get a new strain of fungus [CZ₈₄₆₄(F₂)] which was isolated from a patient with pulmonary aspergilloma. It was identified mycologically as Aspergillus oryzae (Ahlburg) Cohn with proliferous phenomenon. No strain with similar characteristics has been found in the literature. It grew well on aerophilic and anaerobic media. Colonies on Czapek's agar, PDA, Sabouraud's agar, blood agar and malt extract agar grew well at 25℃ 28℃, 37℃. About 7% the conidial heads proliferated into secondary heads.