The epigenetic profile of germ cells, which is defined by modifications of DNA and chromatin, changes dynamically during their development. Many of the changes are associated with the acquisition of the capacity to support post-fertilization development. Our knowledge of this aspect has greatly increased— for example, insights into how the re-establishment of parental imprints is regulated. In addition, an emerging theme from recent studies is that epigenetic modifiers have key roles in germ-cell development itself — for example, epigenetics contributes to the gene-expression programme that is required for germ-cell development, regulation of meiosis and genomic integrity. Understanding epigenetic regulation in germ cells has implications for reproductive engineering technologies and human health.