BACKGROUND Selective depletion of CD4+ T lymphocytes is common in both primary and secondary immunodeficiencies. Idiopathic CD4+ T lymphocytopenia (ICL) cases are defined as a persistent CD4+ T lymphocyte count of less than 300x10(6) cells/L and/or less than 20% of the total T-cell count. METHOD A 40-year-old woman, with a history of psoriasis and paracetamol allergy, presented with persistent warts of the hands and condylomas of the ano-genitalia. Histological and virological analysis was carried out on genital and cutaneous lesions and peripheral blood. RESULTS Serology for HIV-1, HIV-2, Epstein-Barr virus and parvovirus B19 were negative. There was lymphopenia of 10% CD4+ cells, with normal numbers of total leukocytes; there were no other-abnormal immunological findings. DNA analysis of cutaneous lesions revealed HPV-49 and HPV-3 in the hands and HPV-6 in the genital region. CONCLUSIONS The cause of the ICL in this patient is unknown. HPV is not known to be an immunosuppressive agent; it remains to be determined whether the HPV-associated lesions are the cause or the result of immunosuppression.