Evidence is submitted suggesting malignant melanoma may be an estrogen-dependent tumor, similar in its behavior to cancer of the breast, kidney and endometrium. Evidence is based largely on case reports showing activation of melanoma following estrogen administration. Other arguments include epidemiological studies showing a peak incidence of melanoma in females in the third and fifth decades, periods of high estrogen activity; the response of human melanoma to antiestrogenic hormone; and studies demonstrating endocrine influence in animal melanoma.