An agar plate test is described to determine the growth inhibition of dermatophytes by fungicides applied to fabrics. Trichophyton rubrum and Epidermophyton floccosum, two major causative agents of tinea pedis (athlete's foot), were used as test organisms. The assay was capable of distinguishing between direct contact effects and diffusion of fungicide into the agar medium, and could be used semi-quantitatively. The method included an essential sterilization stage to prevent interference by micro-organisms contaminating the test materials. Loss of fungicide efficacy due to the sterilization procedure required careful control.