Although deep trichophytic infection often occurs in immunocompromised patients, the immune deficiency in such patients has not been clarified. A 28-year-old man who suffered from recalcitrant trichophytic granuloma and tinea universalis during treatment for SLE with corticosteroid is described here to define the immunological abnormalities. In addition to routine immunological tests, we evaluated the patient's innate and specific immune functions to dermatophytes, including T cell, natural killer (NK) cell and neutrophil functions and activation of the complement cascade. We measured the minimum inhibitory concentration (MIC) of itraconazole for the isolated fungus and its concentrations in the patient's serum and pus. Trichophyton (T.) rubrum was constantly isolated from the exudates of the patient's skin lesions, although the concentrations of itraconazole in his serum (198 ng/ml) and lesions (210 ng/ml) were sufficient to inhibit the growth of the isolated fungus in vitro. Specific cell-mediated immune responses, determined by T cell stimulation and IFN-gamma production, were evoked following stimulation with trichophytic antigens. The patient's innate immunity, assessed by activation of the complement cascade and neutrophil-mediated phagocytosis, was not impaired. The number of circulating NK cells was markedly decreased (0.2% of the peripheral blood mononuclear cells), and was associated with low NK cell activity against K-562 cells even though lymphopenia had improved. The deficiency of innate immunity mediated by NK cells might be responsible for a part of the persistence of trichophytic granuloma in our case. Dermatophytes usually affect the horny layer of the skin and do not invade the living layers because the host immune system uses various mechanisms to eliminate the fungi. Both specific T cell-mediated immunity and nonspecific immunological mechanisms provide host defense against fungal infections. An adaptive immune response is usually preceded by innate immune responses mediated by neutrophils, NK cells, and circulating proteins such as complement components and anti-microbial peptides. However, in patients with localized or systemic immunological defects, granulomatous cutaneous infection of dermatophytes mostly caused by trichophytic fungi may occur [1]. Trichophytic granuloma includes Majocchi's granuloma [2] and disseminated trichophytic granuloma [3]. Recently, we experienced a patient with trichophytic granuloma and tinea universalis caused by Trichophyton (T.) rubrum infection during treatment with corticosteroid for systemic lupus erythematosus (SLE). We describe the clinical details of this patient, focusing on his immunological defects which led to the persistence of the fungal infection.