The sign of Leser-Trélat, which refers to the sudden appearance and rapid increase in size and number of seborrheic keratosis associated with a visceral malignant tumor, is very uncommon. This case concerns a 54-yr-old woman presenting with Leser-Trélat's sign associated with advanced gastric cancer. Seborrheic keratosis faded after resection of the tumor, but returned when the cancer recurred. At that time, 24-h urinary excretion of epidermal growth factor determined by radioreceptor assay was slightly elevated. Epidermal growth factor may play a part in the development of Leser-Trélat's sign.