The aim of this paper is to analyze a fragment by Porphyry concerning Seleucid history and transmitted by Eusebius of Caesarea's Chronicon. A short introduction on this work (par. 1) will be followed by a defense of the authorship of the fragment as Porphyrian, and by a cautious suggestion to assign it to the Contra Christianos (par. 2). In the last section, the fragment will be examined at length and its ideological background will be highlighted. In particular, the account of Seleucid kings' deaths shows that Porphyry turned to sources favorable to that dynasty. A critical voice seems to raise only when the author recounts of Demetrius I and of his descendants.