MetaProx is the Database of Metagenomic Proximons: A searchable repository of proximon objects that can be used to find metagenomic genes, as well as their predicted functional interactions and corresponding annotations. Proximons represent a special subset of directons (series of contiguous co-directional genes) where each member gene is in close proximity to its neighbours with respect to intergenic distance. As a result, proximons represent potential operon candidates where some subset of proximons is the set of true operons. Proximons are well suited for the inference of metagenomic functional relationships because predictions do not rely on homology-dependent information that is frequently unavailable in metagenomic scenarios. MetaProx currently includes 4,210,818 proximons consisting of 8,926,993 total member genes. MetaProx is housed at the University of Waterloo in Waterloo, Canada.