In this study we investigated a synergistic effect between the essential oils Origanum vulgare, Pelargonium graveolens and Melaleuca alternifolia and the antifungal compound Nystatin. Nystatin is considered a drug of choice in the treatment of fungal infections, but it can cause some considerable problems through its side effects, such as renal damage. Finding a new product that can reduce the Nystatin dose via combination is very important. Our findings showed an experimental occurrence of a synergistic interaction between two of these essential oils and Nystatin. The essential oil O. vulgare appeared to be the most effective, inhibiting all the Candida species evaluated in this study. Some combinations of Nystatin and P. graveolens essential oil did not have any synergistic interactions for some of the strains considered. Associations of Nystatin with M. alternifolia essential oil had only an additive effect.