Multiple factors appear to influence survival in patients with malignant melanoma. Although at present thickness appears to be the best individual prognostic factor, other variables such as anatomic site of the lesion, ulceration, and level consistently appear in multivariate prognostic models. These multivariate models enable the assessment of patient prognosis for the optimization of treatment as well as the evaluation of future therapeutic trials. Future study of these prognostic factors will hopefully help us to understand the pathophysiology of melanoma and, possibly, unlock the secrets of the biology of this disease.