Eccrine poroma frequently occurs as a solitary tumour, and only a few reports have described the occurrence of multiple lesions. Multiple eccrine poromas, or eccrine poromatosis, may occur in patients who have undergone radiotherapy and/or polychemotherapy. We report here four cases of multiple eccrine poromas in patients who were either undergoing, or had undergone, intensive chemotherapy (from 6 months to 16 years prior to onset). Three patients had non-Hodgkin's lymphoma and one had malignant fibrous histiocytosis. The number of lesions varied from 3 to > 20 in each patient, and all the lesions occurred on non-irradiated skin. The histopathological features were consistent with those of eccrine poroma, Pinkus type. In addition to radiation therapy, intensive chemotherapy may play a role in the pathogenesis of multiple eccrine poromas even many years after treatment.