A short account of some figures will be given which we have accumulated during the nine years of the existence of the mycology laboratory in the General Hospital (Table 1). The overwhelming majority, or to be exact, more than 96% of all hair infections by Microsporum species are caused by Microsporum audouini. The absolute figures represent only a fraction of the total incidence, because even in the hospital certain cases, which are clinically typical and which show clear-cut fluorescence with Wood's light, are not cultured. This, indeed, refers in much higher percentage to cases seen in private practice, and one can only guess how many thousands of cases are seen by dermatologists, general practitioners, and pediatricians. One rather busy practitioner confesses to approximately 60 cases of M. audouini infection per year, and only the hope can be expressed that this is not the average number