The occurrence of the outbreaks of bovine trichophytosis and numbers of people affected by this disease in the Czech Socialist Republic were studied in 1966 to 1977. The effectiveness of the preventive and therapeutic measures against the causative agents of the disease is proved by a marked drop of the number of outbreaks in all months in the mentioned period. The greatest drop was in March (74.9) and April (70.1 annually) and lowest in June to August (24.6 to 27.8 annually). Despite the drop of the number of trichophytosis outbreaks, the number of ill animals slightly rose (+402 heads). The slow decrease of the number of trichophytosis outbreaks in summer requires more intensive therapeutic and preventive activity. Summer emptying of stables, supporting the devitalization of dermatophytes, should be used in the sanitation of the houses. The highest monthly seasonal indices of bovine trichophytosis were found in May and April (more than 13% above the annual average), and the lowest in December (23% below the average) and in November (12.5% below the average). The seasonal occurrence of dermatomycoses in man does not coincide with the seasonal occurrence of the disease in cattle. The seasonal index is at its maximum in winter (January-March), reaching 13-15% above the average. The lowest value of the seasonal index was found in August (20% below the long-term average).