The new field of applied genetic research, genetic toxicology and mutation research investigates the muta- genicity and cancerogenicity of chemicals and other agents. Permanent changes in genes and chromosomes, or genome mutations, can be induced by a plethora of agents, including ionizing and nonionizing radiations, chemicals, and viruses. Mutagenesis research has two aims: (1) to understand the molecular mechanisms leading to mutations, and (2) to prevent a thoughtless introduction of mutagenic agents into our environment. Both aspects, namely, basic and applied, will be treated in the new series Advances in Mutagenesis Research.