Considering the matrimonial policy of Demetrios II of Macedonia (239–229 BC) the authors pay special attention to two questions: (1) the parentage of Demetrios’ first wife, Seleucid princess Stratonice, and (2) the identity of the mother of Demetrios’ son, famous Philip V. According to the tradition, Stratonice was sister of Antiochus II Theos (Just. 28.1.2; Euseb. Chron. 1.249 Schoene; cf Jos. C. Apion. 1.206–207). However, when ascending the throne in 260 Antiochus II was still very young (26 according to Euseb. Chron. 1.251 Schene), and according to the common practice, at about the same time he gave his daughter (also called Stratonice) in marriage to the future Ariarthes III of Cappadocia (Diod. 31.19.6; Euseb. Chron. 1.251 Schoene; Synk. P. 332.6–7 Mosshammer). If that was the case, Antiochus’ daughter was still a child. It is not improbable that the tradition confuses two Stratonices: it was Antiochus’ sister who married the Cappadocian prince ca. 260–258 BC, while his daughter later married the future Demetrios II of Macedonia. The latter marriage was arranged by Demetrios’ father Antigomus II Gonatas and Antiochus Theos, apparently in connection with the end of the 2nd Syrian war in the late 250s. In the middle of the 240s Antigonus Gonatas tried to arrange a marriage of his successor Demetrios to Nicaea, widow of Alexander of Corinth (Plut. Arat. 17.2–5; Polyaen. 4.6.1). The marriage was either never contracted or very short, for Antigonus’ purpose was to capture Corinth controlled by Nicaea, and this end was achieved. Apparently, Stratonice’s position at the Macedonian court was not threatened by the projected marriage of Demetrios and Nicaea. Only when Demetrios married the Epirote princess Phthia (which episode must have been connected with the anti-Aetolian alliance of Macedonia and Epirus), Stratonice had to leave the kingdom of the Antigonids, especially since she had failed to give birth to a son or was childless at all, for her assumed daughter Apama had probably been born by Phthia. It was also Phthia who gave birth to the future Philip V. The fact that Phthia was Philip’s mother can be proved by a very rare dental defect (teeth gemination) which Phthia’s grandfather, the great Pyrrhus, had as well as the Bithynian prince Prusias Μονοvδους (Plut. Pyrrh. 3.6; Liv. per. 50; Val. Max. 1.8.12; Plin. NH. 7.69; Solin. 1.70; Tzetz. Chil. 3.950 = Arr. Bithyn. FGrHist 156 F 29). This heritable disease could come to the Bithynian dynasty via the Antogonids after Prusias I’s marriage to Philip V’s sister Apama, who must have been Phthia’s daughter (Polyb. 15.22.1; Strab. 12.4.3; Hermipp. 3 F 72). After Phthia, who might have been repudiated for political reasons after the fall of the Aeacids’ monarchy in Epirus in the late 230s BC, the place of the queen and (κατα; θεvσιν) future Philip V’s mother (and later of the wife of Antogonus III Doson) could have been taken up by Chryseis, whose descent is not clear. However one cannot discard W.W. Tarn’s opinion that Chriseis was Phthia’s nickname.