The state of the art and perspectives of neutron scattering in structural molecular biology at the beginning of the new millennium are reviewed. Because of the neutron's particular properties, it is possible to obtain information on biomolecular structures, dynamics and interactions that is not accessible to other methodologies and neutron-scattering experiments should play an essential role if we hope to achieve a reasonable understanding of biology at the molecular level. The special advantages of neutrons combined with the progress in biochemistry and molecular biology are powerful reasons to stimulate a rebirth of neutron-scattering experiments in biology in the post genome sequencing era. When the structures of the components of a system are known, the questions are: how do they interact with each other? what is the role of the environment, through hydration and solvation? what is the dynamics underlying the structures? how do they move? All these questions can be addressed by neutron scattering. Key experiments on proteins, membranes and protein-nucleic acid complexes will be presented and the perspectives of the methods will be discussed.