Protein mobility, chromatin movement and the formation of molecular assemblies in the cell nucleus have, until fairly recently, been viewed in a pseudo-static light, even though the dynamics of other cellular regions have been partly, or wholly understood for a number of years. The new science that has recently emerged on nuclear kinetics reveals a nucleus that has mobile proteins, dynamic intra-nuclear compartments and chromatin that is far from being static. This new knowledge has given scientists a deeper understanding of transcription, translation and the cell cycle. With these fundamentals of nuclear operation, has come a greater understanding of genetics and genetic diseases – so much so that, by way of example, diseases of chromatin have as a category, made significant advances. Whilst certain questions relating to protein mobility, chromatin movement and the formation of molecular assemblies have been answered, many key questions still remain. Those remaining questions have now started to be answered by technological developments. This review marshals the latest scientific evidence on the molecular kinetics of the nucleus that has arisen from a number of recent, elegant experiments.