The incidence of cutaneous melanoma continues to increase in many parts of the world including the United States. The American Cancer Society predicts that there will be approximately 53,600 new cases of melanoma in the United States during 2002 and that there will be 7,400 deaths from melanoma during the same time period. Increased understanding of the underlying mechanisms and risk factors involved in the induction of this deadly disease will require the use of suitable animal models of melanoma. To date, the induction of cutaneous melanoma with ultraviolet radiation (UVR) alone has been observed only in a few diverse animal models: a South American opossum, Monodelphis domestica; a hybrid fish, Xiphophorus; several stocks of transgenic mice; and in Angora goats. Most of these models are not completely suitable due to: 1) the target cell for melanoma formation; 2) the location of the melanocytes in the skin (i.e.- dermal as opposed to epidermal in humans); or 3) problems associated with husbandry and experimental manipulation. Recent studies have identified a mouse, the hepatocyte growth factor/scatter factor (HGF/SF) transgenic mouse, as an attractive model with which to study the induction of melanoma following a single, neonatal exposure to a moderate dose of UVR.