Understanding how a single cell, the fertilised egg, can develop into all the tissues in the body has been referred to as one of the two great problems facing biology; the other is how the brain works. To be working on the early human embryo is a reward in itself. To see such knowledge applied to improve the lives of infertile couples provides special rewards. There are considerable technical challenges in these activities due to the paucity of experimental material, particularly in the human. A major intellectual challenge is to understand the mechanisms that regulate early embryo development, especially the role of signal molecules intrinsic to the embryo and those that are maternally derived. Central to this issue are notions of embryo autonomy and plasticity; the extent to which the same genotype can give rise to different phenotypes in response to environmental perturbations and the need to discover how severe such changes have to be to induce irreversible changes that can compromise the health of the offspring. Research areas that could be fruitful include stress-induced causal effects, cell signalling and the concept of ‘quiet metabolism’. Managing assisted conception practices and their associated risks requires a regulatory framework to ensure the safety and efficacy of the new technologies. However, there is a danger of over-regulation, a cultural phenomenon characterised by a rise in audit and decline in trust. The challenge is to devise regulation in assisted reproduction technologies proportionate to the risks. The ultimate rewards will come from understanding how the human genome operates in functional terms. The ideal system in which to study this is the human blastocyst, an autonomous, functional group of mammalian cells.