The Networks on Circular Chromosome (NetCirChro) tool has been developed by the NIAID Bioinformatics and Computational Biosciences Branch (BCBB) to enable users of the network visualization platform Cytoscape to overlay networks onto a circular chromosomal map. Data selection is synchronized between Cytoscape and the NetCirChro plug-in, allowing users to leverage Cytoscape’s rich features for navigation, search, filtering, and highlighting of complex microbial genome datasets. NetCirChro helps scientists discover the potential role of gene organization in functional regulatory networks. It also assists researchers in understanding the functional properties of neighboring genes.