Effects of thyme oils extracted from nineThymus vulgarischemotypes, cinnamon oil(Cinnamomum zeylanicum), cinnamaldehyde and carvacrol were studied on growth ofMalassezia furfurandCandida albicans.The last three substances and the carvacrol chemotype of thyme oil were the most efficient against the two yeasts. Yeast growth was monitored throughout eight days under log-step concentrations (1 μg/mL-1000 μg/mL) of these four substances. MICs (minimum inhibitory concentrations) and MLCs (minimum lethal concentrations) were also determined by two different methods: poisoned food and dilution-neutralization methods. MICs and MLCs values obtained by the former are lower than those determined by the latter.M.fitrfurwas observed to be more sensitive to cinnamon oil and cinnamaldehyde, whileC. albicanswas more sensitive to thyme oil and carvacrol. It was also found that essential oil activity is mainly due to their respective major components.