Thirty-four arylpropanoids and related compounds were evaluated in vitro for antifungal properties. Among them, 22 phenyl-, 4 naphthyl-, and 4 phenanthrylpropanoids; naphthalene; phenanthrene; and 2-chloro-1-hexyl-1-propanone were tested against dermatophytes by the agar dilution method. alpha-Halopropiophenones exhibited a broad spectrum of activities against Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum, and Epidermophyton floccosum, with MIC values between 0.5 and >50 microg/mL. Keto, alcohol, and alpha-haloketo propyl derivatives of naphthalene and phenanthrene also showed very good activity against all dermatophytes tested, clearly showing that in these series, a halogen atom is not necessary for activity. Phenanthryl derivatives were more active (MICs, 3-20 microg/mL) than naphthyl ones (MICs, 3-50 microg/mL). A structure-activity relationship study was carried out and aided in establishing the structural requirements of arylpropanoids for antifungal activities. Because dermatophytes are a group of fungi that characteristically infect the keratinized areas of the body, these new series of antifungal compounds open the possibility of discovering new topical antifungal drugs for the treatment of dermatomycoses, which are frequently very difficult to eradicate.