The use of molecular biology and cytogenetic methods and the development of knowledge regarding the molecular basis of melanocytic tumors in recent years has been on the rise. Topics of interest include not only diagnostic and predictive pathology, but also genetic counseling and molecular classification of melanocytic lesions. The following text discusses the current knowledge on the molecular basis of malignant melanoma, the use of molecular biology and cytogenetic methods, especially in the differential diagnosis of melanocytic lesions, and the difficulties of predictive testing.