The new field of applied genetic research, genetic toxicology and mutation research investigates the mutagenicity 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.