Seventy-three 1-year-experienced Danish soldiers were examined for tinea pedis as well as onychomycoses before and after a duty period of 6 months in ex-Yugoslavia. The incidence of fungal infections was 16.4% before and 32.3% after their duty period abroad. At first investigation Trichophyton rubrum and T. mentagrophytes were dominant but onychomycosis and tinea pedis were found as well. In contrast, Candida albicans was the predominant pathogen in the second investigation. We explain this by means of the more aggressive nature that yeasts can show when host-parasite relations are disturbed or compromised. Twelve soldiers with positive mycology were offered treatment and the final investigation showed a cure rate of 50%. This result is satisfactory in view of the difficult sanitary conditions.