Preventive measures against tinea pedis were discussed based on our mycological studies using foot-press method and house dust cultures. 1) Untreated patients with tinea pedis frequently disseminate pathogenic fungi into the environment, but dissemination could be easily controlled by simple application of antifungal agents. 2) A high proportion of dermatophytes disseminated in house dust perished naturally within a month under dry conditions, while under moist conditions they survived several months or more. Therefore, humid areas such as the floor and carpet of a bathroom should be cleaned or washed regularly. 3) Adhesion of dermatophytes onto healthy feet usually happens in public spaces where people enter without shoes. Wearing socks cannot prevent dermatophyte adhesion. Cleaning the feet by wiping with a towel or washing with soap seemed to be an effective prophylactic measure after stepping into such spaces.