o-Methoxycinnamaldehyde has been isolated and purified from powdered cinnamon. The compound inhibits the growth and toxin production of mycotoxinproducing fungi. The substance completely inhibited the growth of Aspergillus parasiticus and A. flavus at 100 ,tg/ml and A. ochraceus and A. versicolor at 200 ,ug/ml. It inhibited the production of aflatoxin B1 by over 90% at 6.25 ,tg/ml, ochratoxin A at 25 ,ug/ml, and sterigmatocystin at 50 ,ug/ml. The substance also displayed a strong inhibitory effect on the growth of five dermatophytoses species, e.g., Microsporum canis (minimum inhibitory concentration, 3.12 to 6.25 ,tg/ml).Interscience, New York.