The Nucleic Acid Database (NDB; http://ndbserver.rutgers.edu/) is a mature resource that provides information about crystalline macromolecules that contain nucleic acid. The NDB distributes information about structure through the NDB Web site and the ftp server. There are an NDB Atlas, instructional pages and a help desk available. The NDB began when nucleic acid structural biology was most concerned with relatively simple structures. Today, the NDB deals with highly complex molecular assemblies. The new demands of the science and of the user community have led to a proposed improvement in content, query capabilities and informatics infrastructure for the NDB. This will also provide better integration with the Protein Database (PDB).