The incidence of malignant melanoma of the skin in the white population worldwide is rising and the mortality from this tumour is also rising. It is assumed that this trend will proceed also in coming years. While in 1970 in the Czech Republic 3.2 new cases of malignant melanoma per 100,000 population were reported, in 1990 the rate was already 8.1 and at present the number of notified cases is close to 10/100,000 population. An important risk factor for the development of malignant melanoma is solar radiation, in particular its UV component. Specially intermittent exposure of the skin to intense, even brief exposure to solar radiation with subsequent sunburn is very dangerous, in particular during childhood. People with type I and II skin are particularly threatened. The increased risk of development of malignant melanoma correlates also with the increased number of acquired melanocytic naevi. Investigation and evaluation of risk factor analyses facilitates screening of people at risk and their early treatment. In the clinical diagnosis four types of malignant melanoma of the skin are differentiated: lentigo maligna melanoma (LMM), superficially spreading melanoma (SSM), nodular melanoma (NM) and acrolentiginous melanoma (ALM). The author mentions the characteristics of different forms and signs which facilitate their early detection.