Ageing is the progressive decline of physiological integrity over the lifespan, leading to chronic diseases and poses a major health and economic burden on society. While biological sex is an important determinant in the pathophysiology of many age-related diseases (e.g. cardiovascular conditions), clinical approaches are rarely tailored to the sex of the patient. Therefore, there is a need to understand the differences in molecular ageing trajectories between males and females to better cater for treatments that are aimed at delaying the onset of ageing with a sex-specific focus. Epigenetic changes, specifically DNA methylation, are one of the primary hallmarks of ageing and epigenetic changes across the lifespan appears to be influenced by sex. Several studies have also demonstrated that epigenetic age accelerates age-related diseases. Interestingly, pre-menopausal females display lower epigenetic age than males of the same age however after menopause females tend to “catch up” and display similar epigenetic ageing rates as males. This is in line with epidemiological data showing that, while females have a longer life expectancy than males, they have a lower quality of health towards the end of their lives. There are also sex differences in DNA methylation within specific tissues, but it is unknown whether these sex-specific differences in DNA methylation with ageing are specific or common between different tissue types. I will be demonstrating a comparison on how the sex-specifc differences in DNA methylation patterns affects ageing for muscle and blood tissues.