We have evaluated the combined antifungal effects of the essential oil from Eucalyptus globulus or its main component 1,8-cineole with ketoconazole. Checkerboard microtiter tests were used to analyze their effects against three Candida and six Trichophyton species. The susceptibility of the Trichophyton species to E. globulus essential oil differed distinctly. The fractional inhibitory concentration indices (FICIs) against the tested Candida species ranged between 0.09 and 0.38 for ketoconazole combined with E. globulus essential oil or 1,8-cineole, indicating significant synergism between ketoconazole and the oil samples. Similar experiments using Trichophyton species resulted in FICIs between 0.28 and 0.63, indicating relatively weaker combined effects than those observed with Candida species. Thus, the data reported here show that the anti-Candida effects of ketoconazole can be significantly improved in the presence of E. globulus essential oil or 1, 8-cineole.