Phylomes are complete collections of phylogenetic trees for each gene encoded in a given genome. The advent of the sequencing era has resulted in an exponential increase in the number of fully sequenced genomes. This, coupled with the improvements in tree reconstruction algorithms, have made phylome construction a tool used more and more often for the analysis of genomes. Reconstructing a phylome implies the generation of large amounts of data in the form of multiple sequence alignments and phylogenetic trees. PhylomeDB was first created to serve as storage to all this data, where users could not only download whole phylomes, but also browse through trees and alignments of their choice that had been reconstructed in the phylomes. It currently contains more than 120 public phylomes spread through the three domains of life. The amount of trees and alignments found in the database has already exceeded 1.5 million. In recent years phylomeDB has also become a referent for orthology and paralogy predictions inferred from the phylogenetic trees it stores. For each tree found in the database, phylomeDB maps speciation and duplication events to the tree from which orthology and paralogy relationships between sequences can be inferred. This is complemented by a direct link to metaPhOrs (1], which creates consensus lists of orthologs and paralogs obtained from some of the major tree databases. Also, lists of complete predictions can be downloaded for a complete phylome. One of the main features in phylomeDB is the enriched visualization of stored trees. Interactive images, created using ETE (2], allow the user to visualize additional information about the sequences being displayed and to perform several modifications such as changing the root of the tree or the order of the leaves. It also contains links that can provide the user with more information about the sequences used to reconstruct the phylome and also links to other major protein databases.