Structural biology is an expanding field. It is also the oldest of the biological disciplines, originating with the anatomists and comparative anatomists of the Renaissance, such as Versalius and Morgani. The introduction and improvement of the compound light microscope in the 19th and early 20th centuries produced an explosive era of discovery in histology, embryology, and cytology, which provided the scientific basis for modern biology and medicine. The introduction of the electron microscope in the 1950s began a second epoch of growth in structural biology, with many new and exciting revelations in the fine structure of cells and tissues, and the marriage in the 1960s of ultrastructure and biochemistry produced a vigorous new hybrid discipline, cell biology, in which structure-function relationships are paramount. More recently, immunohistochemistry and hybridization histochemistry have been added to the morphologist's repertoire of available technologies.The present goal of structural biology is the achievement of a more complete understanding of cellular structure in relation to the molecular mechanisms involved in cell processes. Therefore, structural biology now encompasses the full range of such relationships, from the organization of tissues to molecules. At the macromolecular level, the structure and biochemistry of the cell are inextricably interdependent, and they merge in the molecular models constructed by theoretical biologists. New insights are currently emerging into the macromolecular structures that are involved in the interaction of the cell with other cells and components of the extracellular matrix, in the role of receptors in signal transduction, in the cytoskeleton and locomotor apparatus, in axoplasmic transport, in synaptic transmission, in protein traffic control in coated and uncoated vehicles, in back-and-forth movement of proteins between the cytoplasm and nucleus, and in the organization of the genome.The launching of Advances in Structural Biology as a new serial publication may require some explanation. First, structural biology now has a very broad range and is highly diversified; and second, research papers on structure, biochemistry, and function often appear in widely disperse journals. Consequently, investigators in specialized areas often find it difficult to maintain an integrated view of their own field of work, let alone an overview responsibility to specialists and generalists in providing a dedicated forum for a wide range of representative current subjects in structural biology.