Cinnamic aldehyde was emulsified in water (optionally in presence of a non-ionic surfactant and middle chain glycerides) by using some low-energy and high-energy emulsification methods (ultrasonication). The nano- and micro emulsions produced were studied for stability, viscosity and droplet size of the dispersed phase as well as for fungicidal activity against pathogenic fungi of plants (F. culmorum, Ph. cactorum), dermatophytes (T. mentagrophytes, M. gypseum) and molds (S. brevicaulis, A. niger). The nanoemulsions showed better fungistatic activity than the macroemulsions.