Four hundred and ten boys at a boarding school were examined with Wood's light for evidence of erythrasma infection of the toe clefts. Coral-red fluorescence was obtained in seventy (17%) and Corynebacterium, minutissimum was cultured from fifty-eight (14%). In eighteen of the fluorescent cases a fungus was cultured in addition to the C. minutissimum and in four a fungus only was identified.