The inhibitory effect exerted by steroid hormones on the in vitro growth characteristics of dermatophytes is poorly understood. As a hypothesis this inhibition could result from fungal adaptation to the human host. Therefore, in this study the susceptibility of representative anthropophilic, zoophilic and geophilic dermatophytes to hormonal inhibition was compared. As a result, in agar dilution assays progesterone, testosterone, and estradiol proved to reduce fungal growth, whereas hydrocortisone had no such effect. In general, anthropophilic dermatophytes were shown to be more responsive to steroid hormones than geophilic species, suggesting a correlation of steroid susceptibility with adaptation to human skin. However, since fungal response to hormones consisted of growth inhibition and occurred only at steroid concentrations much higher than present in human skin, it cannot be assumed to contribute to this adaptation.