The early observations on the possible induction of transmissible genomic instability after exposure to ionising radiation has received a strong support in the literature during the last 10 years. Aided by new research tools in biology, the better understanding of the mechanisms behind genomic instability leads to conclusions which are challenging the existing views on the interaction and response of the genome to radiation or chemicals. It has become commonly accepted that the full revelation of biological pathways leading to the loss of stability of the genome will also be a major step in the understanding of carcinogenesis. In this short review, some aspects of the recent knowledge and their implications are discussed. Copyright 1998 Elsevier Science B.V.