Forty cases of dermatopathic lymphadenopathy were found in a series of 906 consecutive lymph node biopsies (4.8 per cent). The histologic development and progression of the disease was correlated with the clinical state of the patient. In 35 of 40 cases the patients had active skin disease at the time of the biopsy; one of the remaining five patients had Hodgkin's disease, one had multiple myeloma and one had secondary syphilis. In the other two, no organic cause was found. In nine cases (22.5 per cent), the histological pattern typical of dermatopathic lymphadenopathy was associated with malignant lymphoma. Except for two biopsies, which showed coexisting malignant lymphoma and dermatopathic lymphadenopathy, no histologic features were found which distinguished patients with malignant lymphoma from the remainder. While the pathogenesis of the lymph node changes remains obscure, the histologic features suggest that it is at least in part an immune response, although the nature of the responsible antigen is unknown.