We constructed a tentative genealogic tree of 13 inbred rat strains using genetic markers identified by the AP-PCR (Arbitrarily Primed Polymerase Chain Reaction) technique, which consists of PCR amplification under low stringency conditions, with only one oligonucleotide as both forward and reverse primers. We obtained discrete-state genotypes of 264 loci, presumably covering the whole rat genome. Computational analysis of this panel allowed the construction of a genealogic tree representing the relations among the 13 strains. The accordance of the present results with available data on the histories of some of these strains validates the use of the AP-PCR technique for studies on phylogeny.