Plasma cells within the infiltrate of primary cutaneous malignant melanoma have been reported as a valuable criterion for the prediction of lymph node metastases. In order to evaluate plasma cells, their prognostic significance and their relationship with other clinical and histological parameters, 132 cases of malignant melanoma (29 plasma cell positive and 103 plasma cell negative) were studied. The Breslow thickness, location, and ulceration were the variables related to the presence of plasma cells. The most important variables in predicting survival were lymph node involvement, clinico-pathological type, age, plasma cells, and lymphatic emboli. The most important variables for disease-free interval were lymph node involvement, plasma cells, and age.