A 34-year-old woman presented with leathery thickening and haemorrhagic lesions of several finger- and toe-nails as first symptoms of an HTLV-I infection. Histology resembled that found in mycosis fungoides. Later signs of T cell deficiency (e.g. Pneumocystis carinii pneumonia) developed. An erythemato-papular exanthema representing T cell lymphoma with Pautrier's abscesses preceded her death 1 year later. The detection of HTLV-I antibodies helped to establish the diagnosis following initial confusion owing to elevation of the T-helper cells and the CD4/CD8 ratio.