Searches for genes involved in the ageing process have been made in genetically tractable model organisms such as yeast, the nematode Caenorhabditis elegans , Drosophila melanogaster fruitflies and mice. These genetic studies have established that ageing is indeed regulated by specific genes, and have allowed an analysis of the pathways involved, linking physiology, signal transduction and gene regulation. Intriguing similarities in the phenotypes of many of these mutants indicate that the mutations may also perturb regulatory systems that control ageing in higher organisms.