Melanoma is the most serious form of skin and mucosa cancer and one of the most malignant tumor at all, which incidence drastically rise for the last few decades. New cases of malignant melanoma in Croatia are rising, too. The person at greatest risk is the light-skinned, while among person with dark skin is rare. Malignant melanoma has big tendency to metastasis (per continuitatem, way of the bloodstream or the lymphatic system). It is very important to detect melanoma as early as possible in which can help as the ABCDE rule. Biopsy with pathohistological verification is the best method to diagnose melanoma. AJCC classifies melanoma in 4 stages. Surgery is often sufficient to cure patients with stage I melanoma. In stages II i III surgery is generally followed with adjuvant therapy with interferon alpha and interleukin 2. Chemotherapy, radiation therapy, or immunotherapy are the most frequent kinds of therapies for stage IV melanoma. Prognosis depends of clinical stages of disease, too. After all, it is very important for population to make the acquaintance of factors of risk, early signs and symptoms of malignant transformation of nevi because prevention is the first step to early diagnosis and complete cure.