As the sole repository for three-dimensional structure data of biological macromolecules, the Protein Data Bank (PDB) is an important resource for research in the academic, pharmaceutical, and biotechnology sectors. Over the years, the methods and speed of structure determination have changed as technology has improved. At the same time the methods for data collection, archiving, and distribution of the structural data in the PDB have also evolved. Concurrently, the community of data depositors and users has expanded. As of October 2003, the PDB archive contains approximately 23,000 released structures and the website receives over 160,000 hits per day. The lessons learned from the development of the PDB may be applicable to the ongoing development of new data and knowledge resources in proteomics.