For around a century, DNA compaction was the only known role for histones. Since the early 1990s we now have a much more “active” view on the nucleosome. We now envision the chromatin as a dynamic environment which is regulated by post-translational modifications in the tails of the histones that protrude out of the nucleosome core. Our laboratory evaluates how histone modifications and chromatin configuration in general impact on the repair of the underlying DNA. Understanding the mechanisms of DNA repair will impact on human health issues such as ageing, immunodeficiencies, fertility or cancer.