The crude and relative survival rates from malignant melanoma of the skin were evaluated in 528 patients diagnosed in Western Australia in 1975-1976. Follow-up of patients to December 31, 1980 was 96% complete. For invasive malignant melanoma the relative five-year survival rates were 85% in men and 89% in women, while in cases of preinvasive melanoma both sexes experienced 100% relative five-year survival. The effects on prognosis of sex, anatomic site, clinical stage, level of invasion and tumor thickness were examined. Invasive melanomas of less than 0.76 mm in thickness also were associated with 100% relative survival. The variation in survival of melanoma patients with geographic location and the relative contributions of early diagnosis and biologic nature to the favorable outcome of melanoma in Australia are discussed.