We compared the level of dermatophyte contamination of the floors of traditional swimming pools and of subtropical swimming paradises, a new type of indoor swimming pool introduced in Belgium in 1981. From the results of routine hygiene inspections over several years and of a comparative study, we can conclude that the floors of subtropical swimming pools are much more highly contaminated by dermatophytes than the floors of traditional swimming pools. This higher degree of contamination is due to the huge number of visitors, the complexity of construction, the choice of materials and the long opening hours. In both types of swimming pools, the predominant species was Trichophyton mentagrophytes var. interdigitale, followed by T. rubrum. Other dermatophytes, such as Microsporum canis and M. gypseum, were isolated sporadically.