BioLayout Express3D is a powerful tool for the visualization and analysis of network graphs. Network-based approaches are becoming increasingly popular for the analysis of complex systems of interaction and high dimensional data. Networks can be produced from a wide variety of relationships between entities. In biology this includes the interactions between individuals, disease transmission, sequence similarity, metabolic pathways, protein interactions, pathways, regulatory cascades, gene expression, etc. BioLayout Express3D has been specifically designed for visualization, clustering, exploration and analysis of very large network graphs in two- and three-dimensional space derived primarily, but not exclusively, from biological data.