Mutations in single genes and environmental interventions can extend healthy lifespan in laboratory model organisms. Some of the mechanisms involved show evolutionary conservation, opening the way to using simpler invertebrates to understand human ageing. Forkhead transcription factors have been found to play a key role in lifespan extension by alterations in the insulin/IGF pathway and by dietary restriction. Interventions that extend lifespan have also been found to delay or ameliorate the impact of ageing-related pathology and disease, including cancer. Understanding the mode of action of forkheads in this context will illuminate the mechanisms by which ageing acts as a risk factor for ageing-related disease, and could lead to the development of a broad-spectrum, preventative medicine for the diseases of ageing.