An obese 18-year-old girl without a history of atopic dermatitis or a systemic immunosuppressive disorder had severe measles with liver dysfunction and pneumonia. For the previous 3 years she had had a chronic untreated generalized Trichophyton rubrum infection. The rash of the measles tended to spare the fungal lesions, where numerous fungi grew in the stratum corneum. Serum IgE level was markedly elevated (>16,000 IU/mL) and decreased after effective antifungal therapy. Delayed skin hypersensitivity reactions to trichophytin and tuberculin were negative, but the immediate skin hypersensitivity to trichophytin was positive. These data indicate that the patient had acquired hyperproduction of IgE with suppression of cell-mediated immunity, that is, acquired impairment of the balance between type 1 and type 2 helper T cells. In this case, chronic T rubrum infection was thought to have a role in driving a normal balance between type 1 and type 2 helper T cells toward type 2 helper T cell-dominant immunity. The result was deterioration of the measles infection and prolongation of the dermatophytosis. (J Am Acad Dermatol 2003;48:S43-6.)