Background: Evolutionary processes, such as gene family evolution or parasite-host cospeciation, can often be viewed as a tree evolving inside another tree. Relating two given trees under such a constraint is known as reconciling them. Adequate software tools for generating illustrations of tree reconciliations are instrumental for presenting and communicating results and ideas regarding these phenomena. Available visualization tools have been limited to illustrations of the most parsimonious reconciliation. However, there exists a plethora of biologically relevant non-parsimonious reconciliations. Illustrations of these general reconciliations may not be achieved without manual editing. Results: We have developed a new reconciliation viewer, primetv. It is a simple and compact visualization program that is the first automatic tool for illustrating general tree reconciliations. It reads reconciled trees in an extended Newick format and outputs them as tree-within-tree illustrations in...