Thirteen cases of malignant lymphoma, exclusive of mycosis fungoides, with initial involvement of the skin, were selected from 391 consecutive patients with non-Hodgkin's lymphoma. Their clinical course was correlated to histological subtype. All patients (5/5) with 'favourable' histology had single indurated plaques without extracutaneous involvement, and remained in complete remission for at least 5 years after local radiation therapy. In contrast, all those with 'unfavourable' histology not lost to follow-up (7/7) suffered relapse or died within a 2-year period. They generally had multiple skin lesions and extracutaneous involvement at diagnosis or shortly afterwards. We conclude that histological subtype is an important variable in predicting clinical course in those with cutaneous malignant lymphoma.