Knowledge about genetic alterations occurring in human tumors has dramatically increased following the development of cytogenetic and molecular techniques. Various alterations have been characterized: chromosomal damages, oncogene activations, loss of genetic material. Some of those alterations, such as c-abl rearrangements in certain leukemias, are characteristic of a certain type of malignancy. However, in most tumors, no such correlation has been demonstrated. We review here the genetic alterations discovered in human malignant melanomas.