Fluconazole-resistant Candida species are an emerging problem. In this report, the in vitro activity of C. zeylanicum against fluconazole-resistant and-susceptible Candida isolates is described. The MICs of the bark of C. zeylanicum ranged from < 0.05-30 mg/ml, and were slightly better than commercially available cinnamon powder. Trans-cinnamaldehyde and O-methoxycinnamaldehyde had MICs of 0.03-0.5 mg/ml. The MICs of selected cinnamon candies and gums generally ranged from 25-100 mg/ml. Five patients with HIV infection and oral candidiasis received a commercially available cinnamon preparation for one week. There of the five patients had improvement of their oral candidiasis. Clinical trials will be necessary to determine the usefulness of cinnamon for the treatment of mucosal candidiasis.