Research on male reproductive ageing is lagging behind research on females but is nevertheless important. We use evolutionary, comparative and molecular approaches to understand how advancing male age effects ejaculate traits, the biological and environmental factors that mediate this effect and the fitness consequences of advancing age for the male itself, its female mate and its offspring. This is important both for understanding how different components of the ejaculate respond to ageing and decipher how each component impacts reproductive success and the fitness of the offspring. We aim to use this knowledge to explore interventions that could delay male reproductive ageing and mitigate the potentially detrimental impacts of paternal age on offspring. We use the tractable model organism Drosophila melanogaster the fruit fly in our research.