A Cox's regression model for survival data has been applied to investigate which of the many clinical and histopathologic parameters have a significant influence on the survival probability of the patients with primary malignant melanoma. The thicker the tumor and the deeper the invasion, the poorer the prognosis. Localization of the tumor on the mucous membranes, ulceration, and presence of epithelioid cells are all bad prognostic signs. The stronger the rim of inflammatory cell infiltrate, the better the prognosis for the patient. Females have better prognosis than males and prognosis aggravate with age. Using these parameters it is possible to make a prognosis forecast for the individual patient. Two patients, one with a favorable set of parameters and another with an unfavorable set, are described.