Cancer is considered the genetic disease with the most complex pathogenetic mechanism. Contrary to normal human tissues, which function in a highly ordered and uniform manner, tumor tissues were considered to develop chaos. Here we propose that analysis of human neoplasia according to the concepts of chaos and antichaos allowed to distinguish two main types of cancers: the hematopoietic cancers, characterized by the orderly antichaos and solid cancers governed by a disordered complex of genetic and molecular events characteristic of a chaotic pattern. Genetic chaos and antichaos have generated rules that can be applied to the diagnosis and therapy of human tumors.