Familial malignant melanoma with dysplastic (pleomorphic) nevus has been the most extensively investigated form of this neoplasm. Searches for dominant oncogenes and tumour recessive genes have been performed in various populations to clarify the pathogenesis of the disease. Some of the them have made in possible to localize the gene of the familial cutaneous melanoma with pleomorphic nevus on 1p chromosome. In various progression stages of this neoplasm different chromosomal abnormalities have been reported, which are only relatively specific of the disease stage. Growth substance (sex steroids, hormones, vitamins, immune factors, ions, prostaglandins, and others) regulate melanocyte proliferation and, perhaps, that of melanoma cells.