Derivatives of the allylamine antimycotic terbinafine (1) with varied substitution at the naphthalene ring system have been prepared, and their antifungal activity has been evaluated. In general, the potency is strongly dependent on the bulkiness of the substituent. Only hydrogen or in some cases fluorine are tolerated as substituents at positions 2-4 and 6-8 of the naphthalene moiety, whereas 5-substituents may be larger in size (F, Cl, Br, Me). Derivatives with fluorine at positions 3, 5, and 7 or chlorine at position 5 showed enhanced activity against yeasts relative to 1. This increase in sensitivity could be intensified by simultaneous introduction of two fluoro substituents at positions 5 and 7. Compound 7q demonstrated 8- to 16-fold improved potency against Aspergillus fumigatus, Candida albicans, and Candida parapsilosis.