Five patients with atopic dermatitis, three males and two females, aged 2 to 17 years, had positive reactions to air allergens (Dermatophagoides pteronyssinus and/or farinae). All the patients suffered from severe recurrent dermatophytosis that responded poorly to antifungal treatment. The results of immunologic evaluation by laboratory tests were normal, except for a decrease in the ingestion phase by mononuclear phagocytes. After diagnosis of immunodeficiency, ketoconazole shampoo was used prophylactically and at the very first signs of recurrence of dermatophytosis, systemic antifungal treatment was started, without concurrent use of macrolides and with monitoring of hepatic function. The fungal infections responded well to this treatment and the patients' quality of life markedly improved.