The nanangenines are newly discovered drimane sesquiterpenoid metabolites from a hitherto undescribed Australian fungus, Aspergillus nanangensis. Isonanangenine B is an acylated drimane bearing an isomeric lactone. Isonanangenine B had modest activity against B. subtilis (IC50 56 μg/mL) but the most cytotoxic of the nanangenines against several tumor cell lines (mouse myeloma NS-1 cell, human prostate DU-145 cell line and human breast adenocarcinoma MC-7; IC50 0.16, 0.9, 0.19 and 0.19 μg/Ml, respectively). The nanangenines did not exhibit Gram negative antibacterial, antifungal or herbicidal activity.